Glossary of Watch Terminology

A

Alarm

A function on the watch that sounds a signal at a pre-set time.

Altimeter

A device that measures altitude, or height above sea level by responding to changes in barometric pressure. This device is important for climbers, walkers, mountaineers and aviators.

Analog Display

A display that shows the time by means of hands and a dial (by both hour and minute)

Analog Watch

A watch with a dial, hands, and numbers or markers that present a total display of 12-hour time span. Analog digital refers to a watch that has both a digital display and hands of a conventional watch.

Aperture

Small opening. The dials of some watches (in French: montres à guichet) have apertures in which certain indications are given (e.g. the date, the hour, etc).

Assembling

Process of fitting together the components of a movement. This was formerly done entirely by hand, but the operations have now been largely automated. Nevertheless, the human element is still primordial, especially for inspection and testing.

Automatic Movement

A mechanical movement that requires no winding because the rotor, part of the automatic mechanism, winds the mainspring every time you move your hand. The first automatic movement was invented in Switzerland by Abraham-Louis Perrelet in the Eighteenth century. When fully wound and left to sit, most automatics have up to 36 hours of reserve power. Mechanical movements are accurate within one minute each day. Automatic movements have gained in popularity the last few years especially with watch connoisseurs and are considered to be Switzerland’s mechanical answer to the popularity of the no-winding-needed quartz movements that are standard in Japanese watches.

Auto Repeat Countdown Timer

A countdown timer that resets itself as soon as the preset time has elapsed and starts the countdown again. It repeats the countdown continuously until the wearer pushes the stop button.

Automatic Watch

A watch whose mainspring is wound by the movements or accelerations of the wearer’s arm. On the basis of the principle of terrestrial attraction, a rotor turns and transmits its energy to the spring by means of an appropriate mechanism. The system was invented in Switzerland by Abraham-Louis Perrelet in the 18th century.

Automatic Winding

(also called “self-winding”) Winding that occurs through the motion of the wearer’s arm rather than through turning the winding stem. It works by means of a rotor that turns in response to motion, thereby winding up the watch’s mainspring. An automatic watch that is not worn for a day or two will wind down and need to be wound by hand to get it started again.

B

Balance Spring

Also known as the hairspring is a very fine spring that causes the recoil of the balance wheel back to return to a neutral position.

Balance Wheel

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

Barrel

Thin cylindrical box containing the mainspring of a watch. The toothed rim of the barrel drives the train.

Battery Reserve Indicator

See “power reserve indicator.”

Bezel

The ring, usually made of gold, gold plate or steel, that surrounds the watch face. The toothed rim of the barrel drives the train.

Bi-directional Rotating Bezel

A bezel that can be moved both clockwise or anticlockwise. These are used for mathematical calculations or for keeping track of elapsed time. Allowing the bezel to be rotated both ways gives maximum flexibility to beginning the timing.

Bracelet

A typical watchband is made up of flexible, adjustable elements that resemble links.

Bridge

Complementary part fixed to the main plate to form the frame of a watch movement. The other parts are mounted inside the frame. All other parts are mounted inside this frame.

C

Cabochon

Decorative stone which has been carved into a round shape.

Calendar

A function that indicates the day of the month, and often the day of the week and the year. There are several types of calendar watches.

Caliber

This term is used to indicate the movement’s shape, layout, or size.

Cambered

Often used in referring to a curved or arched dial or bezel.

Case

The metal housing of a watch’s parts. Stainless steel is the most typically used however titanium, gold, silver, and platinum can also be used. Less expensive watches are generally made of brass and plated with gold or silver.

Caseback

The reverse side of a watch case that lies against the skin. May be transparent to allow viewing of the inner workings of the watch or be solid. Most manufacturers engrave casebacks with their name, water and shock resistance, case metal content and other details.

Chime

The bell-like sound made when a clock strikes on the hour, half hour, etc. Two familiar chimes traditionally found in clocks are the Westminster chime made by the famous Big Ben in London, and the bim bam, a two note chime.

Chronograph

Is simply a watch with a stopwatch function. There are many variations on the chronograph. Generally, the chronographic mechanism is driven by movement of the watch and operated by two buttons on either side. These side buttons are used to start, stop and reset the chronograph. Do not confuse the term “chronograph” with “chronometer.” The latter refers to a timepiece, which may or may not have a chronograph function that has met certain high standards of accuracy set by an official watch institute in Switzerland. Watches that include the chronograph function are themselves called “chronographs.”

Chronometer

This term refers to a precision watch that is tested in various temperatures and positions, meeting the standards set by an official laboratory institute in Switzerland. Most watch companies provide a certificate with your chronometer purchase.

Complication

A watch with other functions more than timekeeping. For example, a chronograph is a watch complication. Other complications coveted by watch collectors include: minute repeater, tourbillon, perpetual calendar, or split second chronograph.

COSC

The official Swiss Chronometer Testing organization in Switzerland that puts every chronometer watch through a rigorous, 15-day testing procedure to verify the watch’s accuracy.

Countdown Timer

A function that allows the wearer keep track of how much of how much time has elapsed. Some countdown timers sound a warning signal a few seconds before the pre-set time has elapsed.

Crown

The button on the outside of the case that is used to set the time and date. It can also be used for winding the mainspring of a mechanical watch.

Crystal

The transparent cover on the watch face. It may be made of glass crystal, synthetic sapphire or plastic.

D

Day/Date Watch

A watch that indicates not only the date but also the day of the week.

Day/Night Indicator

A colored or shaded band on a world time that indicates which time zones are in daylight and which in darkness.

Deployment Buckle

A type of buckle that is expands so that the watch can pop open and fasten using hinged, often adjustable, extenders. Though more expensive than a belt-buckle like closure, a deployment buckle is easier to put on and remove and is more comfortable on the wrist.

Depth Alarm

An alarm on a diver’s watch that sounds when the wearer exceeds a pre-set depth. In most watches it stops sounding when the diver ascends above that depth.

Dial

This is the face of the watch. In high-end watches the numerals, indices and surface designs are applied as separate elements. In less expensive watches, they may be simply printed on the dial.

Digital watch

A watch that shows the time through digits rather than through a dial and hands display.

Direct-drive

A function that allows the second-hand to advance in intervals rather than a smooth sweep for more precise timekeeping. The French term for a direct-drive second hand is a trotteuse.

Dual Timer

A watch that measures current local time as well as at least one other time zone. The additional time element may come from a twin dial, extra hand, subdials, or other means.

E

Elapsed Time Rotating Bezel

A graduated rotating bezel used to keep track of periods of time. The bezel can be rotated so that the wearer can align the zero on the bezel with the watch’s seconds or minutes hand. The wearer can then read the elapsed time off the bezel. This saves the wearer having to perform the subtraction that would be necessary if he/she used the watch’s regular dial.

Engine Turning

Decorative engraving (an old craft), usually on the watch face.

Escapement

Device in a mechanical movement that controls the rotation of the wheels and thus the motion of the hands. It provides the impulse to maintain the oscillations of the balance wheel or pendulum.

ETA

One of the leading manufacturers of watch movements based in Switzerland. ETA movements are used by many major Swiss watch brands.

F

Face

The visible side of the watch where the dial is enclosed. Most faces are marked with Arabic or Roman numerals to indicate the hours.

Flyback hand

A seconds hand on the chronograph that can be used to time laps or to regulate finishing times for several competitors in race.

G

Gasket

Most water resistant watches are equipped with gaskets to seal the case back, crystal, and crown to protect against water infiltration during normal wear. Every two years once should check the gaskets to maintain the water resistance of the watch.

Gear Train

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

Gold plating

A layer of gold that has been electro-deposited onto a metal; its thickness is measured in microns (1000th of a mm).

Grande Sonnerie

A type of repeater that sounds the hours and quarter hours when the wearer pushes the button.

Guilloche

A style of intricate engraving technique that is popular on watch dials. It is usually very thin, precise lines interwoven to create a surface texture.

H

Hard Metal

A scratch resistant metal comprised of binding several materials, including titanium and tungsten carbide, which are then pressed into an extremely hard metal and polished with diamond powder to add brilliance.

Horology

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

I

Index

An hour indicator on an analog watch dial, used instead of numerals.

Integrated Bracelet

A watch bracelet that is integrated into the design of the case.

J

Jewels

Synthetic gemstones that acts as bearings for gears in the mechanical watch, reducing friction.

Jump Hour Indicator

A jump hour indicator has the same function of an hour hand. It usually shows the hours by means of a numeral in a window.

L

Lap Memory

The ability, in some quartz sport watches, to preserve in the watch’s memory the times of laps in a race that have been determined by the lap timer. The wearer has the option of recalling these times on a digital display by pushing a button.

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 the watch back to zero in order to begin timing the next lap.

Limited Editions

A watch style that is manufactured in a specific amount, number and available in limited quantities. Limited editions are available from most fine watch manufacturers and are considered prized by collectors.

Liquid-Crystal Display

A digital watch display that shows the time electronically by means of the liquid held in a thin layer between two transparent plates. The numbers are made up of seven segments that form the number 8 when all are activated. They are activated by an electronic impulse.

Lugs

The arms of the watchcase that hold the strap or the bracelet.

M

Main Plate

The basic plate on which all the other parts of a watch movement are mounted.

Mainspring

The driving coiled spring of a watch or clock, contained in the barrel.

Manual Wind

A manual wind watch must be wound every day by the crown in order to run, thus powering the watch.

Marine Chronometer

Highly accurate mechanical or electronic timekeeper enclosed in a box (hence the term box chronometer), used for determining the longitude on board ship.Marine chronometers with mechanical movements are mounted on gimbals so that they remain in the horizontal position is necessary for their precision.

Measurement Conversion

A highly accurate mechanical feature, usually consisting of a graduated scale on the watch’s bezel, that lets the wearer translate one type of measurement into another -- miles into kilometers, for instance, or pounds into kilograms.

Mechanical Movement

A mechanical movement based on a mainspring which is wound by hand; when wound, it slowly unwinds the spring in an even motion. An automatic mechanical requires no winding because of the rotor, which winds the mainspring every time you move your wrist.

Micron

Unit of measurement that measures the thickness of the gold coating. 1 micron = 1/1000mm.

Moon-phase

A window in a watch face that indicates which phase the moon is.

Mother-of-Pearl

The shimmering interior shell of the freshwater mollusk that is sliced thin and used on watch dials. While most have a milky white luster, mother-of-pearl too comes in other colors such as silvery gray, gray blue, pink and salmon.

Movement

The inner mechanism motor of watch that keeps time and moves the watch’s hand, calendar, etc. Movements are either mechanical or quartz.

P

Pedometer

A function that counts the number of strides taken by the wearer by responding to the impact of the wearer’s steps.

Perpetual Calendar

A calendar that automatically adjusts for the months’ varying length and for leap year. Perpetual calendars, which can be powered by quartz or mechanical movements, are programmed to be accurate until the year 2100.

Platinum

One of the rarest of precious metals, platinum is also one of the strongest and heaviest, making it a popular choice for setting gemstone jewellery and watches. Platinum used in jewellery and watches is at least 85 to 95 percent pure.

Power Reserve

The amount of energy reserve stored up to keep a watch running until it stops. The remaining power is sometimes indicated by a small gauge on the dial.

Power Reserve Indicator

A feature of a mechanical watch that shows how much longer the watch will operate before it must be wound again.

Pulsimeter

A scale on a chronograph watch for measuring the pulse rate.

Push-piece

Button that is pressed to work a mechanism. (The push-pieces on chronographs, striking watches, alarms, etc.)

Q

Quartz Crystal

A tiny piece of synthetic quartz that oscillates at the rate of 32.768 times a second, dividing time into equal segments.

Quartz Movement

A movement that allows a watch to keep time without being wound. A quartz movement is generally more accurate than a mechanical movement.

R

12-Hour Recorder (or Register)

A subdial on a chronograph that times periods of up to 12 hours.

Repeater

A function that chimes the time when the wearer pushes a button.

Rotating Bezel

A bezel (the ring surrounding the watch face) that can be turned. It has various timekeeping functions.

Rotor

The part of an automatic watch that winds the movement’s mainspring.

S

Sapphire Crystal

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

Screw-Lock Crown

A crown that can be fastened into the case to make the watch watertight.

Second Time-Zone Indicator

An additional dial that can be set to the time in another time zone. This function allows the wearer to simultaneously keep track of local time and the time in another country.

Shock Absorber

Resilient bearing that is intended to take up the shocks received by the balance staff and thus protects its delicate pivots from damage.

Skeleton Case

A watchcase with a transparent front or back that allows the wearer to view the watch’s movement.

Slide Rule

A function, consisting of logarithmic or other scale on the outer edge of the watch face that can be used to do mathematical calculations.

Solar Compass

A compass that lets the wearer determine the geographical poles by simply rotating a bezel.

Solar Powered Batteries

Batteries in a quartz watch that are recharged via solar panels on the watch face.

Split Seconds Hand

Actually two hands, one a flyback hand the other a regular chronograph hand. When the wearer starts the chronograph, both hands move together. The wearer can stop the flyback hand and regulate chronograph hand. Thus called the ‘split seconds hand’.

Stainless Steel

An extremely durable metal alloy that is practically immune to rust, discoloration and corrosion. It can be highly polished, thus representing a precious metal. Because of its strength, stainless steel is often used even on casebacks of watches made of other metals. Steel has become a popular setting for diamonds.

Stepping Motor

The part of a quartz movement that moves the gear train, which in turn moves the watch’s hands.

Sterling Silver

A white and highly reflective precious metal. Sterling silver refers to silver that is 92.5 percent pure.

Stopwatch

A watch with a seconds hand that measures intervals of time.

Swiss Made

A watch is considered Swiss if its movement was assembled, started, adjusted and controlled by the manufacturer in Switzerland.

Swiss A.O.S.C. (Certificate of Orgin)

A mark identifying a watch that is assembled in Switzerland with components of Swiss origin.

Sweep Seconds-Hand

A seconds-hand that is mounted in the center of the watch dial.

T

Tachymeter

A function on the chronograph watch that measure the speed at which the wearer has traveled over a measured distance.

Telemeter

A telemeter determines the distance of an object from the observer by measuring how long it takes sound to travel that distance. It consists of a stopwatch, or chronograph, and a special scale, usually on the outermost edge of the watch face.

30-Minute Recorder

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

Timer

The instrument used for registering intervals of time without any indication of the time of day.

Titanium

A metal with slightly darker appearance than stainless steel. It is 30 percent stronger and nearly 50 percent lighter than steel it has been increasingly used in watchmaking, especially sport watch styles. Its resistance to salt water corrosion makes it particularly useful in diver’s watches.

Tonneau Watch

A watch shapped like a barrel, with two convex sides.

Totalizer

A mechanism that keeps track of elapsed time and display it, usually on a subdial.

Tourbillon

A device in a mechanical watch that eliminates timekeeping errors cause by the slight difference in the rates at which a watch runs in the horizontal and vertical positions. The tourbillon consist of round carriage, or cage, holding the escapement and the balance. It continously rotates at the rate of once per minute.

Two Tone

A watch that combines two metals, usually yellow gold and stainless steel in the case of fine watches.

U

Uni-directional Rotating Bezel

A bezel that can be rotated in one direction only and is used to monitor elapsed time. It moves only in an anticlockwise 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 error only on the side of safety when timing his dive.

W

Waterproof

A misused term. No watch is fully 100 percent waterproof.

Water Resistance

A water resistant watch can handle light moisture, such as a rain or sink splashes, but should not be worn swimming or diving. If the watch can be submerged in water, it must state at what depth it maintains water resistance.

Winding

An operation consisting in tightening the mainspring of a watch. This can be done either by hand or automatically.

Winding Stem

The button on the right side of the watchcase used to wind the mainspring.

World Time Dial

A dial, usually on the outer edge of the watch face, that tells the time up to 24 time zones around the world.

Y

Yacht Timer

A countdown timer that will sound warning signals during the countdown to a boat race.