Watch Glossary

This section contains an overview of the major parts of a watch.

ALARM
Alerts you to a preset time with a noise or vibration.

ALTIMETER
Measures altitude / height above sea level. A mountaineering essential.

AM/PM INDICATOR
See Day/Night Indicator.

ANALOG/DIGITAL (DUO) DISPLAY, OR ANADIGI
Displays time through an analogue display (with hour and minute hands) and a digital display (graphical digits). Also known as Duo Display or AnaDigi.

ANALOGUE
Uses a dial and hands to display the time.

ANNUAL CALENDAR
Displays the date. Can display anything from Day and Date to Moonphase. See Perpetual Calendar, Moonphase.

APERTURE
Displays certain details like the date on the dial of some watches.

AUTO REPEAT COUNTDOWN TIMER
Counts down to a preset time and then re-starts as soon as the preset time elapses.

AUTOMATIC WINDING MOVEMENT
Operates in the same way as a mechanical manual wind watch with the addition of the Rotor. This is a weighted pendulum that is attached to the back of the movement and spins around the inside of the watch, "automatically" winding it when you move your wrist with normal use. This means that you don’t need to wind your watch, except for once every month or so. If you have an automatic watch that’s stopped, we recommend that you manually wind it about forty times to get the watch back to its full reserve when you wear it again. When you remove your watch, it will then continue to function for the time specified in the manual. This varies but is usually around forty hours.

BALANCE SPRING
Also known as a Hairspring because of its size, it’s a very fine spring found in mechanical watches that causes the balance wheel to recoil, regulating its timekeeping.

BALANCE WHEEL
Controls the watch’s accuracy.

BARREL
Holds the Mainspring in a mechanical watch and controls its Power reserve. Watches with a Double-Barrel have a much longer power reserve.

BEZEL
Used to measure time increments, this is a ring found on the top side of the case around or sometimes beneath the crystal. Available as uni-directional or bi-directional, bezels can be used to begin timing an event at any time by aligning the number twelve at the start point. Fixed bezels are also available. See Uni-Directional Turning Bezel, Bi-Directional Rotating Bezel, Tachymeter Scale.

BI-DIRECTIONAL ROTATING BEZEL
This type of bezel can be turned clockwise and anti-clockwise so that it has great flexibility to begin timing and is used for tracking elapsed time.

BRACELET
This is the strap that keeps the watch face on your wrist. A bracelet is usually made from metal links that can be adjusted to fit your wrist perfectly.

BREGUET SPRING
This is named after Abraham-Louis Breguet, who created a change in the hairspring in 1795. As this spring expands and contracts, it crushes up on either side and therefore disrupts the balance but Breguet’s solution of reducing the size of the last coil and raising it up improves the watch workings and reduces the abrasion on the balance pivots.

BRIDGE
This part is fixed to the main plate of the watch to form the frame of a watch movement.

CALENDAR
This displays the date of the month or the day of the week and the year.

CAMBERED
This term describes a Domed or Arched Crystal.

CALIBER OR CALIBRE
A term that refers to the movement. For over two centuries, the calibre of a movement has denoted the position and size of the wheel train and the barrel.

CASE
This is what the watch’s parts are contained within. Usually made from metal like stainless steel, more expensive metals like gold are sometimes used on more expensive watches.

CHRONOGRAPH
This refers to a watch that has a stopwatch function. It displays the time as well as measuring and displaying elapsed time. Usually, this is operated by two buttons on the edge of the case which start, stop and reset the chronograph. See Split Seconds Chronograph a.k.a. Rattrapante, Mono (Single) Pusher Chronograph, Fly-Back Chronograph.

CHRONOMETER
This is a term only used to describe a watch that’s been rated by the Swiss testing laboratory, Contrôle Officiel Suisse des Chronomètres. During testing, mechanical movements that are accurate to plus or minus 4 - 6 seconds in a day are awarded a chronometer certificate. Quartz movements must be accurate to plus or minus 0.2 seconds in a day, because these don’t vary based on position & temperature. See Quartz Movement, Mechanical Movement, COSC.

COMPLICATION
This refers to a watch that has more than just the ability to display the time. This could be an alarm or calendar, etc.

COSC
This is the acronym for Contrôle Officiel Suisse des Chronomètres. See Chronometer.

COUNTDOWN TIMER
Tells you how much of a preset time has passed.

CROWN
Also known as a winder or winding stem, this is what is used to set the time (hands) on your watch. It’s usually a little knob on the edge of the case and can also be used to wind the mainspring of a mechanical watch. See Screw-Down Crown, Winding Crown.

CRYSTAL
The clear, often glass or plastic and sometimes scratch-resistant sapphire crystal, cover on a watch that covers the dial.

DAY/DATE
This kind of watch displays the day and date.

DAY/NIGHT OR AM/PM INDICATOR
This function tells you whether the time is before or after 12 noon and is usually found in watches with a World Time Display, for example.

DEPLOYMENT BUCKLE
This expandable buckle fastens the strap around your wrist securely. It allows the watch to slip on and snap shut, therefore reducing strain on the strap itself.

DIGITAL DISPLAY
Uses numbers or digits to display the time, rather than hands on a watch face. A popular digital display type is Liquid crystal display (LCD).

DUAL TIME
Shows local time and in another time zone. Usually displayed by an additional hour hand, it is sometimes shown in a smaller dial within the main watch face. See GMT, World Time Display.

DUO DISPLAY
This displays the time in analogue format with hour and minute hands as well as digitally. See Analog/Digital Display.

DIAL
The face of the watch where you read the time.

ELAPSED TIME ROTATING BEZEL
Used to keep track of set periods of time this is a graduated, rotating bezel that can be rotated so that you can align the zero of the bezel with the watch's minutes or seconds hand and then the elapsed time can then be read from it.

EOL
This simply stands for End Of Life and refers to the battery in a Quartz watch.

ENGINE TURNING/TURNED
Also known as Guilloche, this ancient technique is still used by watchmakers today to engrave delicate designs onto metal watch parts.

EQUATION OF TIME OR EOT
This complication displays the difference of true solar time dictated by nature and man’s version, mean solar time. We think of days being 24 hours long but in fact, because of the way that the earth orbits around the sun in an elliptical manner on a tilted axis, there are only four days in a year when the day is 24 hours long: April 15th, June 14th, September 1st and December 24th. For the rest of the year, the days are all shorter or longer and our “mean” time is simply an adjusted version of this.

ESCAPEMENT
This device effectively moves the watch hands by creating the impulses to maintain the oscillations of the balance wheel or pendulum.

FLY-BACK CHRONOGRAPH
This is a chronograph that immediately restarts when it’s brought back to zero.

FUNCTION
This describes something that a watch has, for example, a countdown timer. These are also known as complications.

GEAR TRAIN
These gears transmit power to the escapement from the mainspring.

GMT TIME ZONE
Greenwich Mean Time (GMT) is also known as Zulu Time and UTC (Universal Time Coordinated) and it is the international time standard by which all World Time is set. Agreed in 1884, it remains the same throughout the year and is not impacted by Daylight Saving Time. See Dual Time, World Time.

GOLD PLATING
This is when a thin layer of gold is used to cover something. In terms of watches, this is usually in relation to a gold plated case or bracelet.

GUILLOCHE
Guilloche is also known as Engine Turning and is a delicate engraving technique that’s been used for centuries to etch a design onto metal. See Engine Turning.

HAIR SPRING
This is a really fine spring that’s found inside mechanical watches. It is shortened and lengthened to regulate the watch’s timekeeping. See Balance Spring.

HELIUM ESCAPE VALVE
Used on professional diving watches, this one way valve releases pressure during the decompression that occurs during dive. Helium is used in breathing mixes used by divers but as they dive deeper whilst using a diving bell and decompress the helium, it will seep through into the watch because of its tiny molecules. This can cause the crystal of the watch to pop out.

HOROLOGY
This is the science of time measurement and includes the construction and design of timepieces.

INDEX HOUR MARKER
This is simply an indicator on an analogue watch that is often used in place of a number or numeral.

JEWELS
These are faux gemstones are used as bearings for gear trains and can reduce friction.

JUMP HOUR/MINUTES
This is a display that shows a number that changes on the hour or minute, rather than a hand that rotates continually. The sun, our first means of understanding the notion of time, appears to move around and so a hand on a dial seems like a natural way of telling the time but a jumping display is an alternative way to indicate time. Each new indication is instantaneous and on each hour, the mechanism causes the numbered disc to make one jump forward.

LAP TIMER
This function enables you to time parts of a race, for example, a relay. It’s a function within a chronograph and when a lap is completed, the timer stops and returns to zero, ready to time the next lap.

LEVER ESCAPEMENT
This is when the wheel teeth are locked and unlocked by the two pallets that make up the lever. When the balance engages the other end of the lever, the escape teeth that slide on the inclined pallets lift the lever to move the balance.

LIQUID CRYSTAL DISPLAY (LCD)
Liquid crystal display or LCD as it’s commonly known, is a type of digital display. It’s formed by liquid that’s formed into seven segments and held between two transparent panes. Electronic impulses activate the individual segments.

LUMINOUS
This can refer to the hands or dial on a watch, which can help you in reading the time. in dark rooms or our in the street when it’s dark.

LUGS
These are the sturdy arms that are on two sides of the watch case and attach the strap or bracelet to it.

MAIN PLATE
The area that holds all the different parts of the watch.

MAINSPRING
A coiled spring in a mechanical watch that supplies power to the watch movement..

MANUAL WIND MOVEMENT
This refers to a watch that has a crown that you will need to turn by hand in order to maintain the good timekeeping of the watch. Once wound, it should continue to maintain accuracy for around 40 hours. See Automatic Winding Movement, Quartz Movement, Winding Crown.

MARINE CHRONOMETER
This is a very accurate timekeeper that’s used for working out the longitude on a ship. If the marine chronometer has mechanical movements, they’re mounted on gimbals so that they remain in an optimal horizontal position.

MEASUREMENT CONVERSION
This enables you to convert measurements on your watch.

MECHANICAL MOVEMENT
This is essentially a watch that works without an electrical source. It operates on a purely mechanical basis with gears, moving parts and springs and sometimes requires winding in order for it to keep accurate time.

MICRON
This is the term used to measure the thickness of gold plating. One micron is one thousandth of a millimetre.

MINUTE REPEATER
This is a watch that gongs on each new minute, quarter hour and hour.

MONO (SIGNLE) PUSHER CHRONOGRAPH
This is simply a stop watch that’s operated by just one button. Most chronographs have two buttons that they are operated by but a Mono Pusher operates start, stop and reset with just one button. See Split Seconds Chronograph a.k.a. Rattrapante, Fly-Back Chronograph.

MOONPHASE
This indicates the phases of the moon and is usually an aperture in the watch face that contains the information.

MOTHER OF PEARL
A beautiful, natural material that is sometimes used as a watch dial. It has a multicoloured sheen that catches the light very nicely on a watch face.

MOVEMENT
This is the motor that enables a watch to keep time. See Automatic Wind Movement, Manual Wind Movement, Quartz Movement.

NUMERALS
These are an alternative to numbers or index hour markers on a watch face as a way of indicating the time. They are either Roman or Arabic.

PERPETUAL CALENDAR
Displays the date, day, month and leap year cycle. Can also display the year and Moonphase. See Annual Calendar, Moonphase.

PLATINUM
This expensive metal is sometimes used for the case or bracelet on luxury timepieces as it doesn’t tarnish.

POWER RESERVE INDICATOR
This indicates how much wind is left in the main spring, letting you know how much longer the watch will keep time for.

PULSIMETER
Measures your pulse rate on a chronograph.

PUSH-PIECE
This is simply a button that can be pressed on a watch.

QUARTZ CRYSTAL
Quartz crystals are piezoelectric, which means that when they receive mechanical pressure, they generate an electrical charge and vibrate if an electrical charge is applied to them. The reason that they can keep such accurate time is that they can be cut at a consistent size and shape, which enables them to vibrate at thousands of times per second, making them extremely stable resonators.

QUARTZ MOVEMENT
When an electronic watch has a quartz crystal that oscillates when it receives an electrical current. A watch with a quartz movement is usually incredibly accurate.

RATTRAPANTE AKA SPLIT SECONDS CHRONOGRAPH
See Split Seconds Chronograph.

REGULATOR OR REGULATEUR
This arrangement ensures that the minute and hour hands don’t obscure each other as they are separated on two different dials, making it easier to read the time.

RESERVE DE MARCHE
See Power Reserve Indicator.

RETROGRADE
This kind of watch displays the functions in a linear fashion, meaning that the hands travel along an arc and jump back to the beginning, rather than going around in a circle.

ROTATING BEZEL
This is a bezel that can be rotated around the watch face.

ROTOR
This is what winds the mainspring in an automatic watch.

SAPPHIRE CRYSTAL
This is a scratch-proof material that’s a popular choice for the glass of watches. This covers the dial and makes it very clear to view the time.

SCREW DOWN CROWN
This is a crown that is threaded and screwed into a tube in the case to close it and create a water-tight seal. It also protects the crown from bumps and knocks. Unless stated by the manufacturer, do not push or adjust the crown whilst the watch is under water. See Winding Crown, Crown.

SECOND TIMEZONE INDICATOR
This is a separate dial on your watch that can be set to an alternative time zone, enabling you to read the time of two locations very easily. See GMT Time, Dual Time, World Time.

SHOCK ABSORBER
This protects your watch’s pivots by absorbing shocks that might be endured.

SKELETON CASE
This is the transparent back that some watches feature. It allows you to see the internal workings of the watch for an attractive and unusual design feature.

SLIDE RULE AKA NAVIGATION COMPUTER
This device is featured on the edge of a watch face and enables mathematical equations, like conversions.

SOLAR POWERED BATTERIES
These are rechargeable batteries in a quartz watch that are powered up through solar panels on the face of the watch.

SPLIT SECOND CHRONOGRAPH AKA RATTRAPANTE
This is a chronograph that features two centre seconds hands. The extra hand runs in line with the main chronograph hand and can be stopped independently and can then catch up with the original. This Split Seconds hand hand refers to two hands; a flyback hand and a regular chronograph hand.

STAINLESS STEEL
This durable material is a very popular metal for making watch cases out of or, on more expensive watches, the case back may be stainless steel, whilst the case might be made from a more expensive metal.

STOPWATCH
See Chronograph.

STEPPING MOTOR
This is a feature of a quartz analogue movement that moves the watch's hands.

STERLING SILVER
This attractive metal is sometimes used for the face or dial of a watch.

SUBSIDIARY DIAL
This is a smaller dial on a watch face that could be used for a number of functions, for example, the date..

SWISS-MADE
This refers to a watch that was made entirely in Switzerland. That means that the assembly of the movement and the watch itself were started, adjusted and controlled by a manufacturer in Switzerland and that at least half of its moving parts were manufactured there.

SWISS A.O.S.C
This is a certificate that authenticates that a watch was assembled in Switzerland with parts that are of Swiss origin.

TACHYMETER SCALE AKA TACHOMETER
This measures speed over a pre-determined distance and is a common feature on chronograph watches.

TANG BUCKLE
This is a fastening on a watch strap that is a simple loop and pin, like you would find on a belt.

TANK WATCH
Designed by Cartier, it has a rectangular face with bars on the sides.

TIMER
This simply records intervals of time but does not display the time of day.

TITANIUM
This strong yet lightweight material is sometimes used in sports or diving watches.

TOTALISER
This records and displays time that has passed.

TOURBILLION
This part of a watch works to allow for differences in the rate that time is recorded, caused by a watch being on your wrist and therefore being in many different positions.

UNI-DIRECTIONAL ROTATING BEZEL
This is a bezel that can be rotated in only one direction and monitors elapsed time.

VIBRATION PER HOUR OR VPH
The movement of an oscillating element, limited by two opposite positions. This usually vibrates five or six times a second.

WATER RESISTANCE
This is the term used to indicate the extent that a watch can be exposed to water. Find out more about water resistance in Knowledge Base.

WINDING
This is what you do when you tighten the mainspring on a mechanical watch by turning the crown. It can also be done automatically, when the rotor swings when your wrist moves.

WINDING STEM AKA WINDING CROWN
This is the (usually) grooved stem on the exterior of the watch case, that you use to wind the watch hands or the mainspring of a mechanical watch. See Crown

WORLD TIME COMPLICATION
This is a dial on the watch face that displays the time of up to 24 time zones. It usually displays the names of the cities within certain time zones along with their time. A watch with this function is a World Timer.