Watch Glossary
Plain-English meanings for the words you will hear when you shop for a watch, from automatic and quartz to lug width and sapphire crystal.
46 Watch Terms Explained
Automatic
A mechanical watch that winds itself from the motion of your wrist.
Manual-wind
A mechanical watch you wind by hand using the crown.
Quartz
A battery-powered watch regulated by a vibrating quartz crystal. Accurate and low maintenance.
Solar
A quartz watch that charges its battery from light. Citizen's version is called Eco-Drive.
Movement
The mechanism inside a watch that keeps time. Also called the caliber.
Caliber
A specific model of watch movement, often written with a number or letters.
Chronograph
A watch with a built-in stopwatch, usually controlled by pushers on the side of the case.
Complication
Any function on a watch beyond telling the time, such as a date, chronograph or moon phase.
GMT
A watch that shows a second time zone, usually with an extra hand.
World time
A watch that shows the time in many cities or time zones at once.
Moon phase
A display that shows the current phase of the moon.
Perpetual calendar
A calendar that tracks the date, day and month, including leap years, without manual correction.
Power reserve
How long a mechanical watch keeps running once it is fully wound and not worn.
Jewels
Synthetic rubies used as bearings in a mechanical movement to reduce friction.
Rotor
The weighted part inside an automatic watch that spins as you move and winds the mainspring.
Crown
The knob on the side of the case used to set the time and, on mechanical watches, to wind it.
Pusher
A button on the side of the case, most often used to operate a chronograph.
Bezel
The ring around the dial. It can be fixed, or rotate to time dives or show a second time zone.
Lume
Luminous paint on the hands and markers so you can read the dial in the dark.
Lugs
The arms that extend from the case and hold the strap or bracelet.
Lug width
The distance between the lugs, which decides the strap size. Common sizes are 18, 20 and 22 mm.
Lug-to-lug
The length of the watch from the tip of the top lugs to the tip of the bottom lugs.
Case diameter
The width of the watch case in millimetres, usually without the crown.
Case back
The back of the watch. It can be solid steel or a transparent window.
Exhibition case back
A transparent case back that lets you see the movement.
Skeleton dial
A dial with parts cut away so you can see the movement.
Crystal
The clear cover over the dial.
Sapphire crystal
A very scratch-resistant crystal used on many better-made watches.
Mineral crystal
A hardened glass crystal. Less scratch-resistant than sapphire, and common in everyday watches.
Water resistance
How well a watch resists water, shown in metres or ATM. It is a pressure rating, not a depth you should dive to.
ATM
A unit of pressure used for water resistance. 5 ATM is often described as 50 metres.
Dial
The face of the watch, with the hour markers and hands.
Indices
The hour markers on a dial.
Sub-dial
A small dial inside the main dial, often showing seconds, minutes or hours on a chronograph.
Date window
A small opening on the dial that shows the date.
Bracelet
A metal watch band made of links.
Clasp
The fastening on a strap or bracelet. A deployant clasp folds open like a buckle.
Integrated bracelet
A bracelet designed as part of the case so the two flow together with no visible lugs.
NATO strap
A one-piece fabric strap that threads behind the watch, popular for casual looks.
Tachymeter
A scale on the bezel or dial used with a chronograph to measure speed over a known distance.
Hacking
A feature that stops the second hand when you pull the crown out, so you can set the time precisely.
Chronometer
A watch whose accuracy has been tested and certified by an independent body.
Swiss Made
A legal label for watches meeting rules on where the movement, case and final checks happen.
Service interval
How often a watch should be checked and serviced. Mechanical watches are usually serviced every few years.
Gasket
A rubber or synthetic seal that keeps water and dust out of the case.
Hand-wound vs automatic
Both are mechanical. Hand-wound needs winding by you, automatic winds from wrist movement.
Need help?
Not sure what a term means for the watch you like? Ask our team.