Watch Glossary

Watch Glossary James Samson

Are you often stuck with the terminology of watches? Explore our glossary and you should be able find the answer to all your timepiece related questions here!




A function on a watch that will make a sound and/or vibration at a pre-set time.


Measures altitude or height above sea level. Recording ascent and descent, an altimeter watch is an important piece of equipment for climbers, walkers, mountaineers and aviators.

Anadigi display

A display that shows the time both by hour and minute hands (analogue display) and by numbers (digital display). Also known as duo display.


A display which uses continuously moving hands to represent the time.


A small opening found in the diamonds of some watches in which certain indications are given, such as the hour and the date.

Arabic numerals

Numerals expressed traditionally from 1-12.

Atmosphere (ATM)

A unit in describing water resistance. 10 metres of water is equivalent to 1 atmosphere (ATM) of pressure acting on the watch. This unit applies to a stationary watch, as a watch in motion in water will experience greater pressure.

Auto repeat countdown timer

A countdown timer that resets itself as soon as the preset time has elapsed and starts again. The countdown is repeated continuously until the stop button is pushed.

Automatic watch

A watch with a mechanical movement that has an additional mechanism called an oscillating weight. As this weight moves (caused by movement of the wrist), the mainspring is wound. Invented by Abraham-Louis Perrelet in the 18th century.



Balance spring

A very fine spring in a mechanical watch that causes the recoil of the balance wheel. The length and adjustment of its length regulates the timekeeping. This is also known as the hairspring.

Balance wheel

The part of a mechanical watch movement that oscillates, dividing time into equal segments. This is the regulating mechanism that controls the acurate timekeeping of the watch.


A drum that holds the mainspring in a mechanical watch. The toothed rim of the barrel drives the train.


Slim, vertical hour markers, often coloured to match other details on the watch, and usually contrasting with the dial to make them easily readable.


The ring on the outside of the watch case, around the dial, or the rim that holds the watch glass. Some watches feature a Rotating Bezel to measure time or speed.

Bi-directional rotating bezel

A bezel that can be moved clockwise or anti-clockwise. It is used for keeping track of elapsed time.

Bracelet Strap

The metal strap that goes around the wearer's wrist. A watch bracelet is often made up of flexible, separate links that can be removed to adjust the bracelet's length.


A part that is fixed to the main plate to form the frame of a watch movement. All other parts are mounted inside the frame.


The mechanism which fastens the watch strap.




A function that indicates day of the month and sometimes day of the week and the year.


A specific model of watch movement, with an alphanumeric name.


This refers to an arched or curved dial or bezel.


The housing that contains a watch's parts. Stainless steel is most commonly used although titanium, platinum, gold and silver can also be found. Less expensive watches are often made of brass and plated with gold-coloured or silver-coloured metals.


A Stopwatch complication which allows the user to track two different times simultaneously. With smaller Sub-dials to track minutes, hours and seconds elapsed.


A watch that has been vigorously tested in various positions and temperatures to ensure that it meets high standards of accuracy demanded by the COSC, the official Swiss chronometer testing institute. To be called a chronometer, the mechanical movement must achieve an average rate of between -4/+6 seconds per day.


an additional function of a watch beyond standard 12 or 24 hour timekeeping. These might include a date window, moonphase display, tourbillon or chronograph. A watch with any additional function is called a complicated watch.

COSC (Contrôle Officiel Suisse des Chronomètres)

A Swiss group which assesses whether a watch can be considered a Chronometer.

Countdown timer

This allows the wearer to know how much of a pre-set time has passed. Some sound a warning a few seconds before the pre-set time has elapsed.


The grooved button on the outside of the case, used for setting the hands on a watch, and the day and date, where applicable. It is also used for winding the mainspring of a mechanical watch. The crown is also known as a winder or winding stem.


This is the clear cover on top of the watch dial (face). It may be made of glass, plastic, mineral crystal or sapphire crystal (a scratch-resistant synthetic material). Its purpose is to protect the watch face.




A watch that shows the day and the date.

Day/night indicator

A coloured or shaded band on a world time that shows which time zones are in daylight and which are in night-time.

Deployment buckle

A folding buckle sometimes found on steel bracelet straps. As well as being quick to remove and secure when fastened, the buckle is usually concealed by the strap while done up.

Deployment clasp

This is similar to a deployment buckle but refers to a fastening on a bracelet watch.


The section of the watch which displays the time. Often used interchangeably with Face.

Digital display

A watch that shows the time in numbers, or digits, rather than hands and a dial. Liquid crystal display (LCD) is commonly used.

Diver's watch

A rugged watch with a level of water resistance greater than 10ATM. High quality watches will be completely sealed against water, with a Screw-cap Crown to prevent leakage.

Dual time

A watch that shows local time and the time in at least one other time zone. Useful for international commuters, or if you make a lot of international phone calls.




An unassembled watch movement.

Elapsed time rotating bezel

A graduated rotating bezel that is used to keep track of periods of time. The bezel can be rotated so the wearer can align the zero of the bezel with the watch's minutes or seconds hand. The elapsed time can then be read off the bezel, rather than the wearer having to perform a subtraction necessary if he used the watch's regular dial.

Engine turning

This is a centuries-old craft that, today, involves the use of antique machines to engrave delicate patterns on metal watch components, including cases, dials, bezels and movements. It is also known as guilloche.


This is the end-of-life indication in quartz battery powered watches.


Component in a mechanical movement which transfers power from the mainspring to the regulator, therefore maintaining accurate time. The notched wheel train and anchor form part of the movement.



Flyback hand

A seconds hand on some chronograph watches that can be used to time laps or determine the finishing times for several race competitors. It is also known as rattrapante.

Foldover clasp

A clasp which collapses on itself, often closing with a safety catch.


A term used to describe the various different tasks a watch can perform such as chronograph and countdown timer. These are also known as complications.



Gear train

The system of gears which transmits power from the mainspring of the watch to the escapement.


Greenwich Mean Time, which provides the basis for determining worldwide time zones by adding or subtracting hours for different time zones.

Gold plating

A layer of gold that is plated onto a base metal case or bracelet to enhance its looks. The thickness of the plating is measured in Microns.

Grand complication

An extremely rare variety of watch which features three major complications in its movement. An example would be a watch with a chronograph, perpetual calender and mechanical alarm. Highly prized by watch collectors.


An engraving technique sometimes used on watch dials or to decorate watch movements. Achieved with a repetitive turning machine, this fine decoration is found on high-end watches to demonstrate the extensive effort put into their production.




A very fine spring in a mechanical watch that causes the recoil of the balance wheel. The length and adjustment of its length regulates the watch's timekeeping. It is also known as a balance spring.


A mechanical watch which requires the user to wind the mainspring. Usually accomplished by twisting the crown back and forth while it's flush with the watch case. Most modern watches can't be overwound without the assistance of tools, so just stop winding once there is sufficient resistance in the spring.

Heartbeat window

A small skeleton window which reveals the mainspring of the watch, allowing the wearer to see the watch's "heartbeat" as the mainspring coils and uncoils.


The science of time measurement, encompassing the art of designing and constructing watches.




An hour indicator on an analogue watch dial, used instead of numeral.


The symbols other than numerals used to denote the hour points on a watch face.




Synthetic gemstones that act as bearings for the gear trains, reducing friction and wear. They also provide a welcome aesthetic touch when the mechanism is visible in a Skeleton Dial or Window Caseback.





Lap timer

A function in a chronograph watch that allows the wearer to time segments of a race. At the end of a lap, the timer is stopped and then returns to zero to begin timing the next segment.

Leather strap

A watch strap usually made from calf leather.


An illumination function incorporated into the dial to enable the watch to be read in low light. Can be a bulb which can be switched on or off at will, or glow-in-the-dark chemicals inlaid in the numerals, hands or hour markers.


These form part of the bracelet and can be removed in order to adjust the length to fit your wrist.

Liquid crystal display

Liquid crystal display (LCD) watches show a numeric display continuously by means of the liquid held in a thin layer between two transparent plates. The numbers are made up from seven segments that form the number 8 when all are activated. They are activated by an electronic impulse.


The "arms" which protrude from the top and bottom of the watch case. Each lug features a drilled hole. A pin is pushed through the watch strap, which is then fixed into place between the two lugs.




A reduction in the accuracy of a mechanical watch movement caused by exposure to a strong magnetic field, including medical or airport scanners, or powerful speakers. A magnetised watch should be serviced to restore accuracy.

Main plate

The base plate upon which all other parts of a watch movement are mounted.


The primary spring in a watch where the potential energy is stored. Gradually releases over time, regulating the time and providing energy for the movement. The watch will stop when the mainspring is fully unwound.

Marine chronometer

A highly accurate mechanical or electronic timekeeper that is enclosed in a box and is used for determining the longitude on board a ship. Marine chronometers with mechanical movements are mounted on gimbals so they are in the horizontal position that is essential for their precision.

Measurement conversion

A feature that allows the wearer to convert one type of measurement into another. It usually consists of a graduated scale on the bezel or dial.

Mechanical movement

A watch movement that operates without batteries, using only moving parts such as cogs, levers and springs. This is the traditional watch movement and is therefore held in higher regard by watch experts due to the higher difficulty involved in their production.


This is a thousandth of a millimetre and is a measurement used for the thickness of gold plating.

Minute repeater

A function on a watch that sound the time in hours, quarters or minutes.


A complication which tracks the waxing or waning of the moon. Although sometimes used as a decorative feature, the moonphase can be used to infer information on the tides, or to provide an indication of how much moonlight there will that night.

Mother of pearl

The iridescent interior of a freshwater mollusc, that is often used to decorate watch dials. Its colours include milky white, blue and pink.


The motor of a watch that makes it keep time and perform functions.

Multi functional

A watch that can perform different functions, such as a stopwatch or a countdown time, whilst still giving the correct time.



NATO strap

A fabric watch strap, that adds a more casual feel to a watch.


Used to denote the hour points on the watch face, traditionally either Arabic (1 - 12) or Roman (I to XII).



Perpetual calendar

A watch complication that tracks and displays the day, date, month and year without requiring resetting for shorter months or leap years. Found in extremely high end watches.

Physical Vapour Deposition (PVD)

A method of coating a watch with a film of vaporised metal. PVD coatings provide an even coverage which is harder and more resistant to abrasion than electro-plated metals.

Pin buckle

The simple pin-and-hole fastening used on leather watch straps.


Platinum is one of the rarest and most durable of precious metals. It doesn't tarnish and has a radiant, beautiful white lustre. It is a popular choice for prestigious watches set with gemstones.

Pocket Watches

A vintage watch-style that preceded the wristwatch. Pocket watches have a traditional analogue watch face, may be attached to a chain and are carried in the pocket.

Power reserve indicator

A feature of some mechanical watches which indicates how much longer the watch will operate before it needs to be wound again. It is also known as the reserve de marche.


A scale on a chronograph which is used for measuring pulse rate.


A button that is pressed to work a watch function such as a chronograph and an alarm.



Quartz crystal

The slice of synthetic quartz crystal within a quartz movement watch. When an electric current is passed through the quartz it oscillates. It oscillates at the rate of 32.768 hertz, dividing time into equal segments and therefore regulating the time.

Quartz movement

A watch movement that uses a battery running a current through a quartz crystal. Keeps extremely accurate time, but relies on the battery having a charge.




These watches receive radio-controlled signals from a satellite transmitter to ensure highly accurate timekeeping. Radio-controlled watches are accurate to within one second.


A seconds hand on some chronographs that can be used to time laps or determine the finishing times for several race competitors. Also known as a flyback hand.


A regulator what shows hours and minutes on separate dials, or sub dials.


A display which resets back to zero once the cycle has completed.

Roman numerals

Hour markers of I - XII, associated with more classic-looking dress watches.

Rotating bezel

A watch bezel which can be rotated, instead of remaining static.


A weighted piece of metal that spins about when an automatic watch moves. This is the oscillating part of an automatic watch that winds the mainspring.



Sapphire crystal

A crystal, the cover that protects the watch face, made of synthetic sapphire - a transparent, scratch resistant substance.

Screw down crown

A crown which screws down into a threaded barrel to aid a watch's water resistancy.

Screw-cap crown

A cap used to prevent water leaking into the seams around the watch crown. Hinges into place over the crown and screws into place.

Second time zone indicator

An additional dial that can be set to the time in another time zone. This allows the wearer to know the time in two zones simultaneously.

Shock absorber

A resilient bearing which takes up the shocks received by the watch's balance staff and protects its pivots from damage.

Shock resistance

A watch's ability to withstand an impact equal to that of being dropped onto wood floor from a height of three feet.

Skeleton case

A watch case with a transparent front or back, allowing visibility of the watch's movement.


A watch that can withstand splashing with water, but should not be fully submerged as water may enter the watch mechanism.

Splits seconds hand

This refers to two hands - a flyback (rattrapante) hand and a regular chronograph hand. Both hands move together but, to time laps or finishing times, the wearer can stop the flyback hand while the chronograph hand continues. This, in effect, splits the hand in two.

Stainless steel

A durable metal alloy that is almost rust resistant and rarely corrodes or discolours and, therefore, is highly suitable for watch case and bracelets. It is sometimes used on the case backs of watches made of other metals.

Stepping motor

The part of a quartz analogue movement that moves the gear train and in turn moves the watch's hands.

Sterling silver

Sterling silver is a highly reflective precious metal, which is 92.5% pure and is often used in watches.


A watch with a seconds hand that measures intervals of time. When a stopwatch is incorporated into a watch, both the stopwatch and the standard watch are called a Chronograph.


A strip of material to which the watch is attached by the Lugs.


A smaller dial set inside the main watch dial. Used for purposes such as indicating the date or keeping track of elapsed time.

Swiss A.O.S.C.

A certificate of origin - a mark that identifies that a watch has been assembled in Switzerland and has components of Swiss origin.


A legally protected term. Due to the prestige associated with the Swiss watch-making industry, this term is often misused. A watch is considered Swiss-made if the movement is Swiss, the movement is cased up in Switzerland, and the watch undergoes its final inspection in Switzerland. Otherwise the watch may be described as having Swiss parts, but may not be described as "Swiss made".




A numerical scale around a watch bezel. This is used in conjunction with the seconds hand to calculate speed or distance of a moving object.

Thirty minute recorder

A subsidiary dial on a chronograph that can time periods of up to 30 minutes.


A device for registering intervals of time with out any indication of the time of day.


A metal with a silvery appearance that is stronger and lighter than steel. Titanium is used increasingly in watchmaking, especially for sports and divers watches as it is resistant to salt water corrosion.


A watch case shaped like a barrel with two convex sides.


A mechanism that keeps track of and displays elasped time, often on s subsidiary dial.


A tourbillon is found in mechanical watches and is a device that eliminates timekeeping errors caused by the small differences in the rates a watch runs in the vertical and horizontal positions. It consists of a round cage, holding the balance and escapement. It rotates continuously at the rate of one rotation per minute.



Uni-directional rotating bezel

A bezel that can be rotated in one direction only and is used to monitor elapsed time. A ratchet mechanism is often in place to prevent it rotating in the other direction. Often found on divers watches, as the bezel moves in one direction only means the diver can only underestimate remaining air supply.




This refers to the movement of an oscillating element that is limited by two extreme positions. The balance of a mechanical watch usually vibrates at a rate of five or six a second.



Water resistance

A laboratory-assessed standard that details how well a watch can be expected to resist exposure to water without leaking. Based on submersion of the watch in static water. Measured in intervals of 10 metres / 1 ATM.


The International Organisation for Standardisation prohibits the use of the term "waterproof" when describing watches. See Water resistance.


This is the action of tightening the mainspring of a watch. It can be done manually, by means of the crown, or automatically, via a rotor which is made to swing by the movement of the wearer's wrist.

Winding stem

The grooved button on the outside of the case, used for setting the hands on a watch, and the day and date where applicable. It is also used for winding the mainspring of a mechanical watch. It is also known as the crown.

Window caseback

A case with a transparent back, usually mineral or sapphire crystal, instead of a metal back. Allows the interior of the mechanism to be seen when the watch is removed.

World time Dial

A sophisticated complication which allows the wearer to switch between time zones with the press of a button, without manually adjusting the hands. Ideal for frequent international travellers.





Yacht timer

A countdown time which shows or sounds warning signals during the countdown to a boat race.