Horology 101:

This glossary provides definitions for key terms and components related to watchmaking and horology. It serves as a helpful reference for enthusiasts, collectors, and anyone interested in understanding the intricate mechanics and features of timepieces.

Alarm: A complication that sounds at a set time
Amphibia: A type of Russian dive watch
Anti-Reflective Coating: A coating applied to the watch crystal to reduce glare
Antimagnetic: A watch designed to resist magnetic fields
Automatic Movement: A watch movement that winds itself using the motion of the wearer's wrist
Balance Cock: The support for the balance wheel and spring
Balance Spring (Hairspring): A small spring that returns the balance wheel to its neutral position
Balance Staff: The axle of the balance wheel
Balance Wheel: A wheel that oscillates back and forth, regulating the movement of the watch
Barrel: The housing for the mainspring in a watch
Bezel: The ring surrounding the watch face, often used to hold the crystal in place
Blued Hands: Watch hands that are heat-treated to achieve a blue color
Bracelet: The metal band of a watch
Bullhead: A watch with the crown and pushers on the top of the case
Caliber: The specific design or movement of a watch
Carbon Fiber: A lightweight and strong material used in watch cases
Case: The outer shell of a watch that houses the movement
Caseback: The back cover of a watch case
Ceramic: A scratch-resistant material used in watch cases and bezels
Chronograph: A watch with a stopwatch function
Chronometer: A highly accurate watch that has been certified by an official body, such as COSC
Clasp: The mechanism that secures the watch strap or bracelet
Complication: Any feature in a watch beyond the basic display of hours, minutes, and seconds
COSC: Contrôle Officiel Suisse des Chronomètres, the Swiss chronometer testing institute
Côte de Genève: Decorative stripes applied to the movement bridges
Crown: The knob on the outside of the watch case used to set the time and date and wind the watch
Crystal: The transparent cover that protects the watch face
Deployment Clasp: A clasp that allows the watch bracelet to be opened and closed without fully unbuckling
Detent Escapement: A high-precision escapement used in marine chronometers
Dial: The face of the watch where the time is displayed
Diving Bezel: A rotating bezel used to measure dive time
Double Chronograph: A chronograph with two stopwatch mechanisms
Dual Time: A watch that displays two different time zones
Endshake: The slight movement of a gear or wheel in its bearing
Equation of Time: A complication that shows the difference between solar time and standard time
Escapement: The mechanism that regulates the release of energy from the mainspring
Exhibition Caseback: A transparent caseback that allows the movement to be seen
Flyback: A chronograph function that allows the reset of the stopwatch hand without stopping the chronograph first
Foudroyante: A subdial that measures fractions of a second
Frequency: The speed at which the balance wheel oscillates, usually measured in Hertz (Hz)
Frequency Governor: A device that controls the speed of an alarm or repeater mechanism
Gear Train: A series of gears that transmit power from the mainspring to the escapement
Geneva Seal: A quality certification for watch movements made in Geneva
Greenwich Mean Time (GMT): A watch complication that displays a second time zone
Guilloché: A decorative pattern engraved on the dial
Hack Mechanism: A feature that stops the second hand when the crown is pulled out
Hand: The pointers on a watch that indicate the hours, minutes, and seconds
Helical Spring: A coiled spring used in certain watch movements
Helium Escape Valve: A valve on professional dive watches that allows helium to escape during decompression
Horology: The science and art of timekeeping
Incabloc: A shock protection system for watch movements
Indices: The markers on the watch dial that indicate the hours
Jeweling: The process of placing jewels in a watch movement
Jewels: Synthetic sapphires or rubies used as bearings in a watch movement to reduce friction
Jump Hour: A complication where the hour hand jumps to the next hour
Kinetic Movement: A watch movement that generates power from the motion of the wearer's wrist
Lugs: The parts of the watch case that connect to the strap or bracelet
Luminova (Lume): A luminous material used on watch hands and dials
Mainspring: The spring that stores energy to power a mechanical watch
Manual Movement: A watch movement that requires winding by hand
Marine Chronometer: A highly accurate watch used for navigation at sea
Micro-Rotor: A smaller rotor used in automatic watches to wind the mainspring
Minute Repeater: A complication that chimes the time on demand
Minute Track: The markings on the outer edge of the dial indicating minutes
Moonphase: A complication that displays the current phase of the moon
Movement: The mechanism of a watch that keeps time and powers the complications
Oscillation: One complete movement of the balance wheel in one direction and then back
Oscillator: The part of the watch movement that creates the regular, oscillating motion
Pallet Fork: The part of the escapement that interacts with the escape wheel
Patek Philippe Seal: A quality certification for watches made by Patek Philippe
Peripheral Rotor: A rotor that winds the mainspring and is located on the outer edge of the movement
Pilot Watch: A watch designed for aviation use, often with large numerals and a clear dial
Power Reserve: The amount of time a watch will run without being wound or worn
Power Reserve Indicator: A complication that shows how much power remains in the mainspring
Pulsometer: A scale on a chronograph used to measure pulse rate
Quartz Crystal: A crystal that oscillates when an electric current is applied, used in quartz watches
Quartz Movement: A watch movement powered by a quartz crystal
Regulator: A watch with separate dials for hours, minutes, and seconds
Repeater: A complication that chimes the time on demand
Retrograde: A hand that moves in an arc and then resets to the beginning
Rotor: The semi-circular weight in an automatic watch that winds the mainspring
Shock Resistance: The ability of a watch to withstand shocks and impacts
Skeleton Watch: A watch with a transparent dial that shows the movement
Skeletonization: The process of cutting away parts of the movement to reveal its workings
Split-Seconds Chronograph: A chronograph with two stopwatch hands that can be independently controlled
Spring Barrel: The housing for the mainspring
Subdial: A smaller dial within the main watch face that displays additional information
Tachymeter: A scale on a chronograph used to measure speed over a known distance
Tachymeter Scale: A scale on a chronograph used to measure speed
Telemeter: A scale used to measure the distance to an event based on the time it takes for sound to travel
Tourbillon: A complication that counters the effects of gravity on the movement
Unidirectional Bezel: A bezel that rotates in only one direction, typically used on dive watches
Water Resistance: The degree to which a watch can withstand water exposure
Winding Crown: The part of the watch used to wind the mainspring
World Time: A complication that displays the time in multiple time zones
24-Hour Dial: A dial that shows all hours of the day