Like cars and computers, the terminology behind watches is almost as complicated as the mechanics that drive them. Diehard watch nerds throw around familiar terms like “caliber,” “frequency” and “complication” with little regard for an outsider’s knowledge of what they mean in a watch context; they also spout simple jargon that means a lot (“jewels”) and intimidating terms that are actually simple (“Manufacture d’Horologie”). For the timekeeping newbie, a simple glossary will help cut the confusion — consider this your reference point.
Automatic: A mechanical watch that is wound by the motion of the wearer’s wrist, rather than by twisting the crown. The motion of the wrist moves a counterweight (called a rotor) that then powers the mainspring, which turns the watch’s gears.
Balance Wheel: A weighted wheel that oscillates at a constant rate (usually one oscillation per fraction of a second), moving the watch’s gears and allowing the hands to move forward
Bezel: A metal (though occasionally ceramic) ring that surrounds the watch crystal. Often bezels rotate on watches (usually on dive watches) and contain a scale for time or other measurements; some remain stationary or do not have a scale and are purely decorative. (Learn more about different kinds of bezels here.)
Case Back: The reverse side of a watch case that can be removed to access the inside of the watch.
Chronometer: A watch that has been independently tested by the Official Swiss Chronometer Testing Institute (COSC) over the course several days in six different positions at three different temperatures, while remaining accurate to within -4/+6 seconds per day for mechanical watches and ±0.07 per day for quartz watches.
Complication: An additional function of a watch that goes beyond telling the time, like a stopwatch (chronograph), calendar or a moonphase indicator. Complications require additional parts and make a watch more expensive and complex to build.
Crown: A small knob on the side of the watch case that can be used to adjust the time, date and — if your mechanical watch isn’t automatic — wind the watch to keep it running.
Crystal: The clear protective cover that shrouds the watch face, made from either synthetic sapphire, acrylic or glass. Synthetic sapphire is the most expensive to produce, though it is considerably more scratch resistant than either acrylic or glass crystals.
Dial: Also called the face, the dial displays the time and features numerals and markings as well as the hands.
Escapement: An internal component in a mechanical watch that transfers the power from a wound-up watch into the movement of the watch’s seconds hand by driving the balance wheel. This component is responsible for a watch’s ticking noise.
Exhibition Case Back: Also called an “open” case back, this is a transparent cover on the backside of a watch case that shows off the inner workings of the movement.
Frequency: The speed at which a watch ticks (or beats), measured in either vibrations per hour or hertz. Most modern, high-end mechanical watches beat at a frequency of 28,800 VpH (4Hz). Watches that beat at 36,000 VpH (5Hz) or higher are considered to be high-beat watches. A watch’s frequency is controlled by the oscillations of its balance wheel.
Flyback Chronograph: A type of chronograph that can be reset without stopping the chronograph function (which is necessary in a normal chronograph). It’s particularly useful among pilots and other users who need to record multiple times in quick sucession. (Learn more about chronographs here.)
Calendar | Chronograph | GMT | Minute Repeater | Moonphase
Gear Train: A system of gears that transfers power from the mainspring to the escapement.
Hacking Seconds: Also called “stop seconds,” this function will stop the seconds hand when the crown is pulled out. This makes it easier to synchronize a watch with another timepiece.
Indices: The markings on the dial of a watch used to represent the hours in place of numerals. In higher-end watches, these are usually “applied,” or attached to the dial, rather than printed on.
Jewels: Synthetic rubies (sometimes synthetic sapphires) used as bearings at the heaviest points of wear in a watch movement in order to reduce friction between moving parts and increase a movement’s lifespan. Jewels have a naturally slicker surface than metal — for example, the coefficient of friction between two pieces of steel is about 0.58, while the coefficient of sapphire on steel is about 0.15. Jewels are only used to increase the accuracy of the movement and are not for decoration.
Lugs: The protruding pieces of metal at the top and bottom of a watch case where the strap is attached. The two ends of the lug hold a spring bar, which holds the strap in place.
Luminescence: Colloquially referred to as “lume,” luminescence is the glow given off by watch numerals, indices and hands that have been coated with a photoluminescent material (“lumed”). While early watches used radioactive radium to create lume, most modern watches use non-radioactive phosphorescent substances like strontium aluminate.
Mainspring: A torsion spring that becomes tightened when a watch is wound, thus storing the energy of a watch. The force of the spring unwinding powers the watch. The mainspring is housed inside a small drum called a “barrel.”
Manufacture d’Horologie: A French term, usually shortened to “manufacture,” that refers to a watch company that develops its own parts (including its movements) at its own facility (“in-house”), rather than assembling watches from parts made by third-party part suppliers.
Movement: The inner-working mechanism of a watch that can be either mechanical (automatic or hand-wound) or quartz (battery powered). Most watch manufacturers refer to their movements as “calibers.” In a mechanical movement, the main components are a mainspring, a gear train, an escapement and a balance wheel. In a quartz movement, the main components are a battery, a microchip circuit, a quartz crystal and a stepper motor. Many high-end movements (both quartz and mechanical) are manufactured in Switzerland by either watch brands themselves or from large movement makers like ETA and Valjoux, though Japan and even China have their own thriving watchmaking industries.
Quartz: A quartz watch is a battery-powered watch. The battery sends an electric signal via a microchip circuit to a small quartz crystal that then vibrates at a precise rate. Those vibrations regulate a stepper motor that moves the watch hands. Quartz watches are considerably more accurate, more reliable and cheaper than their mechanical counterparts, though mechanical watch diehards don’t find them as appealing because of their simpler internal components.
Retrograde: An indicator on a watch dial that forms a segment of a circle, rather than a full circle. When the indicator goes through a full cycle, it resets back to the zero position by moving backwards. Often used to indicate hours, minutes or dates.
Small Seconds: A small sub-dial separate from the main hour and minute function that displays the seconds.
Skeleton: Similar to an exhibition case back, a skeleton watch shows off the inner workings of the watch, but does so through a transparent or partially cut-out dial so that the movement can be viewed from the front of the watch.
Tourbillon: A type of escapement housed in a rotating cage that is meant to counter the negative effects gravity on a movement. While the movement was originally intended for pocket watches, they’ve moved to wristwatches as a way to showcase the height of a manufacture’s watchmaking abilities, and as such, they command exorbitant prices. (Learn more about tourbillons, here.)
Worldtimer: A watch with a dial that can be adjusted to show the time in 24 different time zones represented by 24 major cities across the globe.