Watch Glossary

"A" is for analog, "B" is for bezel... Learn the ins and outs of your new watch with our A-to-Z watch glossary. Simply select the first letter of the term you're searching for from the navigation below.

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Gemstone and Jewelry Glossary

The watch/clock alerts you with an audible or inaudible (such as a vibration) alarm at a pre-set time(s). Not to be confused with the repeater function found in some fine watches.
The degree of swing in a balance-wheel or pendulum.
Analog - Digital Display
A watch that shows the time by means of hour and minute hands (analog display) as well as by numbers (a digital display).
A watch that shows the time using hour and minute hands.
Annual calendar
A watch showing the day, date (in an aperture, or opening in the dial) month and 24 hours, adjusting automatically for short and long months. Such a calendar needs setting only once a year - from the end of February to the 1st of March.
A window in the dial revealing an indication on a disc beneath the dial, such as a date, month, moon, etc.
The shaft of a wheel or of a key-winding system.
Indicates a watch with any indication of time depending on the sun, moon or stars, such as: equation of time, sun hand, zodiacs, time of sunrise and sunset, moon-phase, sidereal time, and star disc.
Atomic second
The world's absolute time unit that defines the second as more than 9 billion periods. One watch that takes advantage of that is the BeepwearPro, produced by a joint venture between Timex and Motorola, resulting in a timepiece which bases it’s time display on a radio signal (found within the continental United States) in turn based on an atomic clock output.
Automatic Winding: (also referred to as just “automatic”)
A watch with a mechanical movement (as opposed to a quartz or electrical movement) with the addition of the watch’s reserve power being maintained by the motion of the wearer's arm rather than through a daily winding process. A rotor (also referred to as “pendulum”) that turns in response to motion winds the watch's mainspring. If an automatic watch is not worn for a day or two, it is normal to wind down and will need to be hand wound to restart.

Battery Reserve Indicator (or End of Battery Indicator)
Some battery-operated watches have a feature that indicates when the battery is approaching the end of its life. This is often indicated by the second hand moving in two-second intervals instead of each second.
The ring that surrounds the watch dial (or face). The bezel is usually made of gold, gold plate or stainless steel, and may be of a rotating style (such as Uni-directional or Bi-directional), sometimes decorated, and even at times interchangeable.
Bi-Directional Rotating Bezel
A bezel that can be rotated either clockwise or counterclockwise. Often used for mathematical calculations such as average speed, distance, or for tracking elapsed time. Also see: Elapsed Time Rotating Bezel.
Breguet Hands
Watch or clock hands featuring a hole cut into a small disc near their point. Also called moon hands.
Built-In Illumination
Artificial lighting source within a watch that allows viewing of the dial in darkness, usually button activated. An example might be Seiko's Lumi-Brite, or Timex’ Indiglo technology. Not to be confused with “Luminous”, which refers to numbers and/or markers, which glow in the dark due to being treated with a light emitting material, usually tritium.

A feature that shows the date, and often the day of the week. There are several types of calendar watches. Most calendar watches show the information digitally through an aperture on the watch face. Some chronograph watches relay the information via sub-dials.
A chime within a watch, usually to sound the time, which involves more than two gongs.
The bottom (back) of a watchcase, which may be opened to access the movement. Many upscale watches feature screwdown casebacks, considered of higher quality, craftsmanship, and durability.
The edge, or side, of a watchcase, often defined as the area between the bezel and the caseback.
CET (Central Europe Time)
Central Europe mean Time, it is the time of the first time zone, just eastward the zero time zone, 1 hour in advance on UTC time (UTC +01:00). Italy adopts CET time since 1893.
CEST (Central European Summer Time)
Daylight saving time, 1 hour in advance on CET time.
Chapter Ring
A ring on the dial upon which the hour numeration/markers are engraved.
A watch that incorporates a stopwatch function, which may be started and stopped to time an event. There are many variations on the chronograph, some operating with a center seconds hand keeping time on the watch's main dial, though likely the most common configuration is the use of sub-dials to show elapsed hours, minutes and seconds. Others show elapsed time via a digital display. Some chronographs can be used as a lap timer (see "flyback hand"). The accuracy of the stopwatch function will commonly vary from 1/5th second to 1/100th second depending on the chronograph. Some may track elapsed time up to 24 hours. Watches incorporating the chronograph function are themselves called "chronographs." More complex chronographs may incorporate specialized scales on the watch face and/or bezel facilitating different functions, such as determining speed or distance (see "tachymeter" and "telemeter"). NOTE: the terms "chronograph" with "chronometer" are not interchangeable (see “chronometer”). The latter refers to a timepiece certified by an official watch institute in Switzerland to meet certain high standards of accuracy, and may or may not have a chronograph function.
A multi-part mechanism providing an additional horological function to the hours, minutes and seconds of a watch. Complications may include chiming, alarms, animations, chronograph, and calendar and astronomical mechanisms. As a rule, timepieces with complications are considered more valuable, and at times more collectable, than their simpler counterparts, the ultimate example being the “Caliber 89”, built by Patek Philippe and the most complicated portable timepiece to date. Also see: Grand Complication.
COSC (Contrôle Officièlle Suisse des Chronomètres)
The three timing laboratories of Switzerland's official chronometer-inspection bureau.
Countdown Timer
A function that lets the wearer keep track of how much of a pre-set period of time has elapsed. Some countdown timers sound a warning signal a few seconds before the time runs out. These are useful in events such as yacht races, where the sailor must maneuver the boat into position before the start of a race.
Also called a stem or pin, a crown is the button on the outside of the watchcase that is used to set the time and date. In a mechanical watch the crown also winds the mainspring. In this case it is also called a "winding stem". A screw in (or screw down) crown is used to make a watch more water resistant. The crown actually screws into the case, dramatically increasing the water-tightness of the watch.
The transparent cover on a watch face made of glass crystal, synthetic sapphire or plastic. Better watches often have a sapphire crystal, which is highly resistant to scratching or shattering.
See Caseback. Also the name of the hinged “cover” found on many pocketwatches.

Depth Alarm
Feature on a divers' watch that “sounds” audibly and/or visually when the wearer exceeds a pre-set depth.
Depth Sensor/Depth Meter
A device on a diver’s watch that determines the wearer's depth by measuring water pressure. It shows the depth either by analog hands and a scale on the watch face or through a digital display.
The area specific to the watch face. Dials can and do vary dramatically, textured or smooth for example, one of the many things that make the variety of watches so fascinating.
Digital Watch
A watch that shows the time through digits rather than through a dial and hands (analog) display. NOTE: a digital watch is not necessarily (albeit usually in the modern era) an electronically powered watch. An example of a mechanical digital might be some of the models by Chaumet, or any of several digitals produced prior to the advent of quartz movement.
Diving Watch
A watch tested to a water resistance of 200M or greater. Usually features a uni-directional rotating bezel and a screw-on crown and back, as well as a metal or rubber strap as opposed to leather, and occasionally, a wet-suit extension. Some, such as the Citizen Divemaster, feature the addition of digital timer and depth gauge.
Dual Time Zone
A watch capable of tracking time in two time zones simultaneously. This may be done with multiple faces, though collectors much more highly seek the quality of a watch able to achieve such a feat within a single face and movement, especially when involving a complicated mechanical or mechanical automatic movement (multiple zones are easily achieved in an electronic watch, which while very accurate is not considered as a rule very collectable). An example of a dual time zone within a single dial and movement might be the very collectable models produced by Gevril, which not only showed the time(s), but also “am” and “pm” within both the local and alternate zones.
Dust Cover
An additional cover hinged over the caseback of the watch, or the cuvette of a pocketwatch. Almost unique to pocketwatches, this feature may occasionally be found in select very upscale wristwatches.

The main part of the movement, before its assembly is completed, made up of the baseplate, going-train and mainspring.
A solar conversion panel and energy cell combination which powers an equipped wristwatch by charging from any light source, thus operating via a limitless free power supply. No conventional battery change is ever required.
Elapsed Time Rotating Bezel
A graduated rotating bezel (see “rotating bezel") used to keep track of elapsed time. The bezel can be turned so the wearer can align the zero on the bezel with the watch's seconds or minutes hand. After a period of time passes, the elapsed time is read off the bezel, thus eliminating the subtraction necessary if the watch's regular dial were used.
Elapsed Time Indicator(s)
Refers to chronograph registers that show elapsed time in minutes and hours once the chronograph is started.
The increasingly rare art of applying enamel coloring to the case and/or dial of a watch, sometimes considered the most difficult of the decorative arts. Enamel is a glass-like substance colored by the addition of metal oxides, which, after being powdered and mixed with oils to form a paste, is then applied to a surface before being vitrified by furnace. The result is often intricate and beautiful, and is usually found on vintage timepieces with the occasional more recent exception.
Engine Turning
The technique of engraving a pattern on a watchcase or dial, usually with a lathe. Also used in the decoration of the interiors and movements of many antique pocketwatches, often with spectacular results.
Specific combination of gears in a mechanical movement that controls the rotation of the wheels and thus the motion of the hands, converting the energy of the mainspring into equal units of time.

Form Watches
Refers to timepieces featuring unconventional or sophisticated cases, i.e., an unusual geometric shape, or even in the form or silhouette of various objects.
Flyback Hand
A seconds hand on a chronograph that can be used to time numerous events within a specific timespan. As the chronograph function begins, both the flyback hand and the regular chronograph seconds hand go into motion. To record the timing of the first event, the flyback hand is stopped while the regular hand continues uninterrupted. After recording the time of that first event, the push of a button will cause the flyback hand to "fly back", or catch up with the constantly moving elapsed-time hand. This process may be then repeated for additional smaller events within the larger being tracked by the main chronograph hand.

Gear Train
The system of gears that transmits power from the mainspring to the escapement.
Geneva Seal
The hallmark featuring the Geneva arms (the eagle and key) found on a watch movement, certifying that it conforms to the highest official standard of traditional Geneva watchmaking, and is a timepiece of outstanding quality. The State of Geneva instituted it in 1886 in order to provide a guarantee of the origin and the craftsmanship of clocks and watches made in Geneva. The criteria include 12 technical absolute requirements related to the manufacturing of the movement. Only manual and automatic (self winding) movements may be awarded the Geneva Seal.
GMT (Greenwich Mean Time)
Also known as UT time. A time measured with astronomical methods, corresponding to the mean solar time of the zero meridian.
Gold Plated
A layer or layers of gold electroplated to a base metal. Some upscale watches, Movado for example, may use many layers to increase durability, looks, and value.
Grand Complication
Pocketwatch with a total of 12 complications arising from the three main areas of mechanical complication in watchmaking: the perpetual calendar, featuring day, date, month, leap-year cycle, the 24 hours of the day and the moon-phase; the chronograph, featuring split-seconds and elapsed-time registers; and lastly, the chime; with Grand Strike, Small Strike and minute-repeater.
Grand Strike
A mechanism utilizing hammers striking gongs within a watchcase, which first strikes the hour sound, and then the quarter hour sound (sometimes numeric) upon reaching the three, six, and nine positions, but only the hour chime on the hour.

Integrated Bracelet
A watch bracelet that is incorporated into the design of the case.

Synthetic sapphires or rubies that act as bearings for gears in a mechanical watch. The jewels reduce friction to make the watch more accurate and longer lasting.
Julian Date
A day numbering system to avoid the incorrect dating of the same day, due to disagreements of different historical calendars. This system uses a cycle called the Julian Period, of 7980 years, which begins at noon on January 1, 4713 B.C., and ends at 3267 A.D. Days are numbered sequentially starting from that date, which is itself numbered zero. As an example, January 1st, 1996, at 12 noon, began the Julian day 2,450,084.

Refers to the Seiko line of Kinetic watches. This innovative technology has a quartz movement that does not use a battery. Movement of your wrist charges a very efficient capacitor that powers the quartz movement. Once the capacitor is fully charged, mens models will store energy for 7-14 days without being worn. Ladies models store energy for 3-7 days. Of course, if the watch is worn every day the capacitor is continually recharged. The watch alerts you to a low capacitor charge when the seconds hand starts to move in two-second intervals.
Krysterna Crystal
A crystal built of material originally developed by the eye glass industry. Ranged in between a mineral and sapphire crystal. More scratch resistant than a mineral crystal and more shatter resistant than a sapphire crystal.

Lap Timer
A chronograph function that lets the wearer time segments of a race. At the end of a lap, he stops the timer, which then returns to zero to begin timing the next lap.
Leap Second
Second added (or removed) to the scale of UTC time, in such a way to keep the difference between UTC time and the Earth rotational time UT1 below 0.9 second. The leap second is inserted on decision of the International Earth Rotation Service.
Liquid Crystal Display (LCD)
A digital watch display that shows the time electronically by means of a liquid held in a thin layer between two transparent plates. All LCD watches have quartz movements.
The longitude of a place on the Earth surface is the angle formed at poles between the meridian of that place and the zero meridian.
The “arms” extending from a watchcase to facilitate the attachment of a watch band or bracelet. Taken from the old English slang for “ears”.
Refers to numbers and/or markers that glow in the dark due to being treated with a light emitting material, usually tritium.

Measurement Conversion
A feature, usually consisting of a graduated scale on the watch's bezel, that lets the wearer translate one type of measurement into another. An example might be miles into kilometers.
Mechanical Movement
A movement powered by a mainspring, working in conjunction with a balance wheel. A purely mechanical movement is not an automatic, and may require daily winding.
Parallel line(s) of measurement spaced equidistant around the globe, passing across the earth’s surface from pole to pole. For example, meridians spaced 15 degrees apart indicate the 24 time zones.
Old name for CET time.
Moon Phase
A complication that illustrates the timing of the phases of the moon. The average period of a lunar cycle is 29 days, 12 hours, 44 minutes and 2.8 seconds.
The inner mechanism of a watch that keeps time and moves the watch's hands, calendar, etc. Movements may be mechanical, automatic, or quartz.

See Rotor
Perpetual Calendar
A complication showing the day, date, and month, and corrects for months of different lengths as well as leap years.
Power Reserve
In simplest terms, refers to the timespan over which a mechanical watch will operate after being fully wound. In a finer watch, this ideally should be forty hours or greater.
Power Reserve Indicator
A feature that shows when the watch will soon need a new battery or winding. A battery reserve indicator on a quartz watch informs the wearer when the battery is low. Often this is indicated by the seconds hand moving at two or three-second intervals. Seiko's Kinetic watches are quartz watches that do not have a battery (see Kinetic). When a Seiko Kinetic needs to be wound, the seconds hand will also move in two-second intervals.
Pure Swiss
A watch that is made entirely in Switzerland. Being made entirely in Germany also qualifies for the title, as does a watch with percentages of construction shared uniquely between these two sources.

Quartz Movement
A movement powered by a battery, and involving the induced vibration of a quartz crystal. Quartz movements are very accurate, and can be mass-produced thus making them less expensive than a mechanical movement requiring a higher degree of craftsmanship. The resulting watch may have hands (analog readout), or may be completely solid state featuring a digital readout, usually LED in nature.

Rating Certificate
A certificate issued by an observatory or timing laboratory showing the rate variations of a chronometer in different positions and temperatures over a set period of time.
Rotating Bezel
A ring with the capability of being turned surrounding a watch face. Different types of rotating bezels perform different timekeeping and mathematical functions (see “elapsed time rotating bezel," "unidirectional rotating bezel," "bi-directional rotating bezel" and "slide rule").
The part of an automatic (or self-winding) mechanical watch that winds the movement's mainspring utilizing a system of gears and ratchets. It is an unbalanced piece of metal, usually semicircular, that swivels on a pivot due to the motion of the wearer's arm or a winding device. Rotors may be constructed of materials ranging from steel to precious metals, and at times can be found decorated, especially in the instance of a skeleton backed watch.

Sapphire Crystal
A crystal made of synthetic sapphire, which is a transparent, shatter-resistant, scratch-resistant material registering a 9 on the Mohs hardness scale (as does a natural sapphire), indicating a hardness second only to a diamond, which is the only 10. Considered the finest material for watch crystals, it is sometimes coated with a light-absorbing layer to reduce glare and reflection. Breitling watches in particular are known for this.
Screw-Lock Crown
A crown threaded so that can be screwed tightly into the case to make the watch water-resistant. The threads are usually internal within the crown, but on rare occasion may also be found in a unique “center column” configuration, such as is seen on some of the military Tutima watches, among others.
Second Time-Zone Indicator
An additional dial that can be set to the time in another time zone. It lets the wearer keep track of local time and the time in another country simultaneously.
See Automatic Winding
Shock Resistance
A watch's ability to withstand impact. Defined by U.S. government regulation, said impact must equal the watch being dropped onto a wood surface from a 3-foot height.
Slide Rule
A device, consisting of logarithmic or other scales on the outer edge of the watch face, which can be used to do mathematical calculations. One of the scales is marked on a rotating bezel, which can be slid against the stationary scale to make the calculations. Some watches have slide rules that allow specific calculations, such as for fuel consumption by an airplane or fuel weight. Probably the best known, albeit not the only watch to incorporate this feature is Breitling.
Small Strike
A mechanism utilizing hammers striking gongs within a watchcase, which strikes the quarter hour sound (sometimes numeric) upon reaching the three, six, and nine positions, and the hour chime on the hour.
Solar Powered
A watch that uses solar energy (from any light source) to power the quartz movement. The Citizen Solar-Tech models use this technology and provide a 180-day power reserve, so they are able to run continuously.
Stepping Motor
The part of a quartz movement that moves the gear train, which in turn moves the watch's hands.
A watch with a seconds hand that measures intervals of time. When a stopwatch is incorporated into a standard watch, both the stopwatch function and the timepiece are referred to as a chronograph.
A small “secondary” dial(s) on a watch face used for any of several purposes, varying from chronograph functions to calendar displays (not to be confused with a date or day/date window), moon phase, etc.
Swiss Made
At least 50.1% of the cost of the parts in the movement was manufactured in Switzerland.

Tachymeter (tack IM eh ter)
A feature found on some chronograph watches, a tachymeter (also called a "tachometer") measures the speed at which the wearer has traveled over a measured distance.
International Atomic Time, a time computed at a later time with statistical methods for error minimization from the time of about 200 cesium atomic clocks spread in about 60 metrological laboratories in the world.
Tank Watch
A rectangular watch designed by Louis Cartier. The bars along the sides of the watch were inspired by the tracks of tanks used in World War 1, while the tonneau shape (see “tonneau”) was derived from the aerial view of a tank.
Telemeter (tel EH meh ter)
A device that determines the distance of an object from the observer by measuring how long it takes sound to travel that distance. Like a tachymeter (see "tachymeter"), it consists of a stopwatch, or chronograph, and a special scale, usually on the outermost edge of the watch face.
Thirty Minute Recorder (or Register)
A sub-dial on a chronograph (see "chronograph") that can time periods of up to 30 minutes.
Time Zone
Part of the Earth surface where the same time is adopted by convention. Ideally, it is an area framed by two meridians 15 degrees of longitude apart. Sometimes for practical and political reasons, it may be set instead by state borders that approximate the position of the defining meridians.
A space-age metal much stronger and lighter than steel, from which some watch cases and bracelets are constructed. Titanium is also hypoallergenic.
Tonneau Watch
A watch shaped like a barrel, or cushion cut gem, with two convex sides. Also commonly referred to, albeit not necessarily accurately, as tank watches.
A unique device that rotates the balance, lever and escapement as a unit around a single axis, reacting to the changing angle of the watch as it is worn. This added complication theoretically averted irregularities caused to the motion of the balance wheel arising from gravitational pull, thus resulting in more accurate timekeeping. It is thought to have been more useful in pocketwatches, which were more inclined to stay at a single angle for an extended period of time, as compared to wristwatches, which of course tend to vary in angle quite often. Still, some of the finest handcrafted watches in the world feature this ingenious invention, showcasing their manufacturers’ expertise in the fine art of complications.
A material which emits light, usually a pale green, after first having it’s own electrons excited by exposure to light energy. Used to treat watch numbers and/or markers, rendering them viewable in dimly lit situations.
Twelve-Hour Recorder (Register)
A sub-dial on a chronograph (see chronograph) that can record periods of up to 12 hours.
Twenty-Four-Hour Recorder (Register)
A sub-dial on a chronograph (see chronograph) that can record periods of up to 24 hours.

Unlocked Crown Indicator (UCI)
A feature invented, patented by, and unique to the Gevril line of watches, it is a mechanical feature incorporated into the screw-down crown mechanism by which a red vertical “dash” appears in a small window positioned at the three o’clock position should the crown not be fully tightened. When the crown is secured, the red disappears in favor of a color matching that of the dial.
Unidirectional Rotating Bezel
An elapsed time rotating bezel, often found on divers' watches, that moves only in a counterclockwise direction. It is designed to prevent a diver who has unwittingly knocked the bezel off its original position from overestimating his remaining air supply. Because the bezel moves in only one direction, the diver can err only on the side of safety when timing his dive. Many divers' watches are ratcheted, so that they lock into place for greater safety.
See UT.
Universal Time, also called Greenwich Mean Time (GMT), a time measured with astronomical methods, corresponding to the mean solar time of the zero meridian.
Coordinated Universal Time, the official measure of time in the world, it is independent from the time zones. UTC time flows like the International Atomic Time (TAI), except for the insertion of the leap seconds.

Water Resistance
The ability to withstand exposure to water. Water resistance does not necessarily mean the watch can be worn underwater (the exception being specifically indicated dive watches) but rather a given resistance to water splashes. A few watches have been built to amazing water tolerances, such as the Roven Dino Mariana 9000, the first watch to be certified by the Swiss government to be resistant to a depth of 9000 meters.
Week of Year
The first week of year is the week that has at least 4 days in that year (UNI 7180-73 standard). In each year there are at least 52 weeks and no more than 53 weeks.
Winding Stem
The “button” on the watchcase used to wind the mainspring. Also called a "crown." Usually found at the three o’clock position on a wristwatch, but usually at the twelve o’clock position on a pocketwatch, though there is always room for some variance here due to form or function; the three o’clock position on a Hunter’s case pocketwatch, for example.
World Time Dial
A dial, usually on the outer edge of the watch face, that tells the time in up to 24 time zones around the world. The time zones are represented by the names of cities printed on the bezel or dial. The wearer reads the hour in a particular time zone by looking at the scale next to the city that the hour hand is pointing to. The minutes are read as normal. Watches with this feature are called "world timers." Some worthy of note would include the exceptional watches by Patek Philippe, or the now highly collectable IWC Porche, produced in titanium with an 18k gold bezel, between the years 1994-1997.

Zero Meridian
Meridian of the Greenwich astronomical observatory in England.
Zero Time Zone
Time zone centered on the Greenwich meridian in England. This time zone adopts UTC time.
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