Better your watch knowledge by learning these commonplace watch terms.
Altimeter: An altimeter measures altitude, or height above sea level. Recording ascent and descent, an altimeter watch is an important piece of equipment for hikers, climbers, and pilots.
Analog: A term describing a clock or watch having hour and minute hands rather than using an LCD display.
Annual Calendar: A complication showing the date; day and month at the minimum. Many will also display Moonphase. This watch will correctly adjust for short and long months; however, it will not correctly account for leap year.
Aperture: Any opening in the dial that displays watch components or functions such as date, day, month or moon-phase.
Automatic: A type of mechanical watch that is wound by the motion of the wearer’s wrist. The motion of the wrist moves a counterweight (called a rotor) that then powers the mainspring which then turns the watch’s gears. Rolex uses the term “perpetual” in lieu of “automatic,” but the terms are synonymous.
Balance Spring: A delicate spring attached to the balance wheel that coils and recoils to swing the balance wheel to regulate time. The balance spring is also referred to as a hairspring.
Balance Wheel: A weighted wheel that oscillates back and forth at a constant rate, regulating time equally. This works the same way a pendulum works.
Barrel: The drum shaped container that holds the mainspring, thus housing the watch’s power reserve. The size of the barrel directly corresponds to how long the power reserve will hold. A double barrel will increase the power reserve.
Beat: The vibration of tick of a watch; about 1/5 of a second. The sound is produced by the escape wheel striking the pallets.
Bezel: A ring that surrounds the dial (face) and retains the crystal. Often made of precious metals or unique materials. A bezel can be used to measure speed, distance or elapsed time.
Bi-Directional Rotating Bezel: This type of bezel is used to track elapsed time. They can turn clockwise or counter-clockwise.
Bridge: A part that is fixed to the main plate to form the frame of a watch movement. All other parts are mounted inside the frame.
Caliber (Calibre): The term identifying movements from their architecture, origin, reference and maker. It is part of the movement identifying the position and size of the wheel train.
Caseback: the reverse side of the watch case, lying flat on your wrist. Some watches feature an exhibition caseback that is transparent allowing you to see the movement.
Chronograph: A chronograph is a watch that not only indicates the time but is also equipped with an additional mechanism (operated manually by push buttons) which makes it possible to measure periods of time, from a fraction of a second to 12 hours.
Chronometer: A precision watch, finely set and tested in various positions and temperatures, for which an official certificate has been issued. The test is performed by the official Swiss testing laboratory called the Controle Officiel Suisse des Chronomteres (COSC) and watches go through a rigorous 15 day test.
Complication: A multi-part mechanism providing an additional horological function, providing more information that just the time. Complicated functions include minute repeater, tourbillion, perpetual calendar, split second chronograph and more.
Crown: Device with which to wind the watch. A crown can be a screw down version or pull out. Crowns are also used to set the time and the calendar.
Crystal: The clear cover protecting the dial from dust and damage. Typically made of glass, mineral or sapphire, or acrylic.
Cyclops: A small magnified lens found on the crystal that is located above the date to make it easier to read.
Day/Night (AM/PM) Indicator: A feature that indicates whether the indicated time is AM or PM. This feature can be found mostly (although not limited to) in watches with a GMT/Dual time display or a World Time Display to help know whether it is day or night in the other time zones.
Deployant Buckle (Deployment Buckle): A type of watch band buckle that hinges closed. When unclasped it unfolds making it easier to take on and off. “Deployant” is the correct term. “Deployment” is the incorrect version often used by Americans.
Dial: Also referred to as the face, the dial displays the time and features numerals and markings to show the hours, minutes, and seconds or more depending on the complications of the watch.
Dive Watch: A dive watch is a water-resistant watch, but not all water resistant watches are dive watches. True dive watches meet specific standards for diving; like ISO 6425, which requires the watch to be water resistant to at least 200 meters. Usually features a uni-directional rotating bezel and some form of illumination.
Dual Time: Measures both current local time and least one other time zone. It can be found in a twin dial, extra hand or subdial. Also referred to as World Time.
Duo Display: A display that shows the time both by hour and minute hands (an analogue display) and by numbers (a digital display). This is also known as AnaDigi display.
EOL: This is the End-Of-Life battery indication in Quartz-powered watches. Generally the seconds begin to tick once in 4 seconds indicating that the power is low and it is time to change the battery.
Escape Wheel: The last wheel in a going train; works with the fork or lever and escapes one pulse at a time.
Escapement: An internal component in a mechanical watch the transfers the power from a wound up watch into the movement of the watch’s seconds hand by driving the balance wheel at a steady rate. Most modern watches use a “lever escapement,” comprised of an escape wheel and a lever with two pallets. The escape wheel is connected to the gear train (which receives energy from the mainspring) and the lever and pallets lock and unlock the escape wheel at a steady rate. This component is responsible for a watch’s ticking noise.
Exhibition Caseback: Also referred to as a skeleton or open caseback, this shows off the movement through a second crystal located on the back of the watch.
Fly-Back 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 succession.
Frequency: The speed at which a watch ticks (or beats), measured in either vibrations per hours of 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.
Gasket: A rubber, neoprene or plastic ring used to seal the gaps between the case and the case back, crystal and crown to prevent water or dust from entering the case and damaging the movement inside.
Gear Train: A system of gears that transfer power from the mainspring to the escapement.
GMT: Also known as Greenwich Mean Time, it is the international standard of time that the world is set to. Every time zone is set against GMT. In watches, a GMT reference refers to the ability to show dual time zones with a second hour hand, primarily found in a 24-hour mode to determine day from night.
Guilloche: An engraved ornamental pattern, often used on watch dials, comprised of intricately intertwined lines typically made by a rose engine. However, many guilloche patterns are stamped or machine engraved via CNC Mill. There is a very noticeable difference in light reflection when comparing a true rose engine turned guilloche versus a stamped guilloche. Unfortunately, some of the most beautiful guilloche work is then covered with paint or enamel which makes it difficult to discern from stamped or machine engraved guilloche.
Hairspring: The very fine spring, no thicker than a strand of hair, that vibrates the balance wheel and causes it to recoil. Also called a balance spring.
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.
Hand-wound: Referring to a mechanical watch that doesn’t automatically wind. Hand-wound watches are powered by manually turning the crown to wind up the mainspring. Automatic watches do not require hand winding but are able to be hand wound.
Horology: The art and/or science of measuring time.
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. Prior to the use of ruby cabochons, pivots were usually made of brass.
Jumping Hour/Minutes: Instead of a hand continuing to move, a “jumping display” uses numerals seen through an aperture, which instantly change on the hour. Some watches also feature “jumping minutes”, although jumping hours are more commonly paired with retrograde minutes.
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.
Luminous: Luminous (lume) markers and hands are made by applying glow in the dark coating to the indicator. This allows them to illuminate automatically in the dark.
Mainplate: The base on which all the parts of a mechanical watch movement are mounted.
Mainspring: A spring that becomes tightened when a watch is wound and stores energy for the watch, housed inside a small drum called a barrel. The force of the spring unwinding powers the watch. Also called a balance spring.
Mechanical Watch: Mechanical watches are the most traditional type of watch. They usually consist of about 120-180 individual parts. This is a watch that runs without any electrical source and can consist of manual wind watches or automatic watches.
Minute Repeater: A timepiece that can be made to strike the time in hours, quarters and minutes, by means of a push piece or slide.
Moon Phases: A complication that represents the waxing and waning of the moon as it circles the earth. This complication is shown in a window on the watch dial.
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.
Perpetual Calendar: A calendar complication capable of showing the day, date and month but often includes the moon phase and year. It takes into account short and long months in addition to the leap year.
Power Reserve: The length of time that a mechanical watch can run once it’s fully wound. Most entry-level watches have a power reserve of about 40 hours, though many higher-end watches can run for several days at a time. Sometimes watches will feature a power reserve gauge indicating how fully wound the watch is.
Pusher: A button on a chronograph watch that starts, stops and/or resets the chronograph mechanism. The majority of chronographs have two pushers — one for starting and stopping the mechanism, and another for resetting.
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 enthusiasts don’t find them as appealing because of their more modern, electric components. The feel of history and romanticism is lost in most quartz watches.
Repeater: A high-end complication that chimes to denote the time at the push of a button on the watch case.
Retrograde: A watch using a retrograde feature uses a linear format to show the time rather than the circular dial. The hands move in an arch and then jump back to the beginning.
Rotor: The part of an automatic watch that rotates as it is worn to wind the main spring.
Sapphire Crystal: Sapphire crystals are 2-3 times harder than mineral glass and virtually scratch-proof. They are more brittle so are more likely to crack or shatter than mineral. Replacement cost is substantially higher than for mineral crystals.
Skeleton Watch: A watch with a movement reduced to the minimum material. Built under a transparent or partially cut-out dial, they create attractive, decorative watches that allow you to view the movement from the front of the watch.
Small Seconds: A small sub-dial separate from the main hour and minute function that displays the seconds.
Stem: The shaft that connects the movement’s winding mechanism with the crown fitted on the opposite end.
Subsidiary Dial: Also referred to as a sub dial, it is an auxiliary dial on the face of the watch. This can be used for various functions including the seconds hand and chronograph functions.
Sun/Moon Indicator: An additional complication found on watches, it is a wheel that is partially visible through the dial indicating the sun and moon in a 24-hour period.
Swiss-Made: A watch is considered Swiss-made if its movement is assembled, started, adjusted and controlled by the manufacturer in Switzerland. At least 50% of the value of all the components (not counting the cost of assembly) are Swiss-made and are subject to technical control in Switzerland according to the applicable system.
Swiss A.O.S.C: A mark identifying the watch was assembled in Switzerland with Swiss-made components.
Tachymeter: A tachymeter (also known as tachometer) measures the speed at which the wearer has traveled over the measured distance found commonly on a chronograph. The wearer starts the chronograph when passing the starting point and stops it when passing the finish. The wearer can then read the speed in units per hour off the tachymeter scale.
Telemeter: A telemeter determines the distance of an object from the observer by measuring how long it takes sound to travel that distance. Like a tachymeter, it consists of a stopwatch, or chronograph, and a special scale, usually on the outermost edge of the watch dial. One application of a telemeter would be determining the distance of a storm from its observer. The wearer starts the chronograph at the instant the flash of lighting is seen, then stops it when thunder is heard. A reading can then be taken to determine the distance of the storm from the observer in miles on the telemeter scale.
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. “Tourbillon” is the correct spelling. It should be pronounced like ter-bee-on in English. If you prefer to sound a little more French, barely allow the “n” to be audible. A common misspelling is “tourbillion.” This is a common American misspelling. Note – there should be no “i” before the “on.” A good way to ensure you are not treated seriously by those in haute horology, is to mispronounce this common term which means “whirlwind” in French.
Uni-Directional Rotating Bezel: A bezel that can be rotated in one direction only and is used to monitor elapsed time. A ratchet mechanism is often in place to prevent it rotating in the other direction. It is often found on divers watches as a fail-safe feature which means the diver can only underestimate remaining air supply.
Universal Time: Mean solar time for the Greenwich meridian, but counted from noon to noon.
Water Resistant: The case, crown, push button and glass of a water-resistant watch are made in such a way that no dust or water can penetrate. Watches undergo in-house tests in a laboratory under controlled conditions. Water resistance is often marked on the case and/or dial in feet, meters, and /or ATM (atmospheres).
Waterproof: A prohibited term used when describing the water resistance of a watch. No watch is 100% waterproof according the Federal Trade Commission of the United States (FTC).
World Timer: A dial that contains up to 24 different time zones, found usually on the outer edge of a dial. The time zones are represented by using the names of major cities. The hour in a particular zone can be read by looking at the scale next to the city that the hour hand is pointing to. The minutes are read in the normal way.