Glossary of Watch Terms
The following terms are used liberally throughout this site and in the world of luxury watches.
Analog
Opposite of digital, a watch showing the time using hands.
Aperture
A small opening. Some watch dials have apertures showing the date or the watch's movement.
Ateliér
(French) The small shop in which a watchmaker (or any artist) works.
Automatic Watch
A watch that winds on its own.
Balance
This might be thought of as the very basis of a watch's movement. It's a tiny moving part secured at its base with a hairspring that causes it to oscillate back and forth regularly. In each oscillation, the wheel moves one click, marking off 1/8th of a second.
Bezel
The ring surrounding the watch dial and crystal.
Cabochon
Usually used in reference to a decorative stone set in the watch crown. It can also mean any small gemstone.
Caliber
This term now indicates a kind of watch movement. Calibers (note: the European spelling is "calibres") come in many variations.
Carat
See note under "karat".
Chronograph
A watch set with a stopwatch. Note its difference from chronometer.
Chronometer
This term refers to the stopwatch itself, and more specifically a stopwatch with precision rigorously tested by the C.O.S.C. (see below) in Switzerland.
C.O.S.C.
The Control Officile Suisse de Chronometers, an independent regulatory council that tests and certifies (or fails) watch movements for chronometer status.
Escapement
A set of parts (i.e. the escape wheel, lever, roller) that convert rotary motion into balance.
Etablisseur
French term for a watch assembly factory that does not make its own parts.
EOL
End of Life. In quartz movement, the second hand will start to "jump" every four seconds when the end of battery life is near.
Fly-Back Hand
In a chronograph with analog display, an additional centre second hand (used as a stopwatch) can be stopped and made to return or "flyback" to a zero setting.
GMT
GMT (Greenwich Mean Time), the standard for all international time.
Guilloche
A type of engraving in which thin (often hand machined) lines are interwoven in a pattern.
Horology
The science of time measurement.
Karat
A unit of gold fineness (and gemstone weight). Purity is 24k. 18k gold is 75% pure. Some sources distinguish carat applied only to gemstones, denoting a unit of weight. We have not seen the need to do so on this site.
LCD
Liquid-crystal display. Digital time display.
Luminova
Synthetic material that glows in the dark, used especially in diving watches.
Mother-of-Pearl
Multi-colored shell of any fresh water mollusk, thinly sliced and used on watch dials.
Movement
The assembly of mechanisms and other internal elements of any timepiece.
Perpetual
Any calendar that automatically adjusts for all months and leap years.
Platinum
One of the rarest and also strongest of the precious metals, ideal for setting jewelry.
Pusher
Any button that operates the special functions of watches.
Rattrapante
The flyback hand of a chronograph.
Repeater
A watch that indicates hours with a note or tone.
Rotor
The half disc of heavy metal that rotates and helps wind an automatic watch.
Shock Absorber
A bearing that takes up shocks received by the balance staff, protecting it from damage.
Skeleton
A transparent case that displays the inner materials (especially the movement) of a watch.
Titanium
Silver-gray "space age" metal that is both stronger and lighter than steel. Also resists rust.
Tourbillon
Often cited as the most significant development in watch history, this consists of the regulating mechanism (balance wheel with hairspring) and the lever escapement, which makes one revolution in one minute. It eliminates effects of friction and earth's gravity.
