Accuracy
The degree to which a watch keeps correct time. Usually measured in seconds gained or lost per day.
Acrylic Crystal
A lightweight plastic watch crystal valued for vintage aesthetics, impact resistance, easy polishing, and warm visual appearance.
Alarm Complication
A mechanical or electronic feature that produces an audible alert at a preset time using internal mechanisms.
Analog Display
Traditional time display using hour, minute, and sometimes second hands rather than digital numerical readouts.
Applied Indices
Separate markers attached to the dial surface, creating depth, luxury appearance, and improved legibility compared to printed markers.
Automatic Movement
A mechanical movement powered by wrist motion through a rotating rotor, eliminating the need for daily winding.
Aperture
A window opening on the dial displaying information such as date, day, month, or moonphase indications.
Balance Spring (Hairspring)
A delicate coiled spring regulating oscillations of the balance wheel, determining the movement's timekeeping precision.
Balance Wheel
The oscillating wheel acting as a watch's timekeeping heart, controlling the rate at which gears advance.
Barrel
A cylindrical component housing the mainspring, storing energy that powers the movement and drives the gear train.
Bezel
The ring surrounding the crystal. May be fixed, rotating, decorative, or functional for diving and timing activities.
Bi-Directional Rotor
An automatic rotor designed to wind the mainspring regardless of rotation direction, improving winding efficiency.
Bridge
A structural movement component securing gears, wheels, and mechanisms while providing stability and facilitating assembly.
Buckle
A fastening mechanism securing a strap to the wrist. Common styles include pin buckles and deployant clasps.
Calibre (Caliber)
The specific movement model powering a watch, identifying its architecture, features, dimensions, and manufacturer.
Case
The external housing protecting the movement, dial, and hands from environmental damage and everyday wear.
Caseback
The rear cover of a watch case, which may be solid, transparent, engraved, or screw-down.
Ceramic
A highly scratch-resistant material frequently used for bezels and cases due to durability and color retention.
Chapter Ring
A ring surrounding the dial displaying minute or second markers, aiding readability and visual structure.
Chronograph
A stopwatch complication capable of measuring elapsed time independently from standard timekeeping functions.
Chronometer
A watch certified to meet strict accuracy standards established by an independent testing organization.
Clasp
A metal fastening mechanism connecting strap ends securely around the wrist, often providing quick-release functionality.
Complication
Any watch function beyond basic time display, including dates, chronographs, alarms, calendars, and moonphases.
COSC
Swiss testing authority certifying chronometers that meet defined accuracy standards across various temperatures and positions.
Crown
A knob on the case used for winding, setting time, adjusting dates, and operating certain complications.
Crystal
The transparent protective cover over the dial, commonly made from sapphire, mineral glass, or acrylic.
Date Complication
A display indicating the current calendar date, usually through a dial window or pointer hand.
Day-Date
A complication displaying both the day of the week and numerical date simultaneously on the dial.
Deployant Clasp
A folding metal clasp designed for security, comfort, reduced strap wear, and easier watch removal.
Dial
The watch face displaying time and complications through markers, hands, textures, finishes, and printed information.
Dive Watch
A watch designed for underwater use, featuring water resistance, luminous markers, and typically a rotating bezel.
Dual Time
A complication allowing simultaneous display of local time and a second time zone.
Escapement
A movement mechanism releasing stored energy in controlled increments while maintaining balance wheel oscillations.
Exhibition Caseback
A transparent caseback allowing visual appreciation of the movement, finishing, and mechanical operation.
Flyback Chronograph
A chronograph allowing instant reset and restart with a single button press while timing continues.
Folding Clasp
A clasp using hinged sections to securely fasten the watch while reducing accidental opening risk.
Gear Train
A sequence of gears transmitting power from mainspring to escapement while controlling hand movement speeds.
Geneva Stripes
Decorative movement finishing featuring parallel waves engraved onto bridges, commonly found in luxury mechanical watches.
GMT
A complication displaying a second time zone using an additional hand and twenty-four-hour scale.
Hand-Wound Movement
A mechanical movement requiring manual winding through the crown to maintain stored power.
Helium Escape Valve
A specialized valve allowing trapped helium to exit during decompression, preventing crystal displacement in diving environments.
Indices
Hour markers on the dial, which may be printed, applied, luminous, or crafted from precious metals.
Integrated Bracelet
A bracelet designed to flow seamlessly into the case, creating a unified aesthetic and fit.
Jewels
Synthetic ruby bearings reducing friction and wear within movement components, improving longevity and operational efficiency.
Lug Width
The distance between lugs determining compatible strap and bracelet sizes for a specific watch.
Lugs
Projections extending from the case that secure straps or bracelets to the watch body.
Lume (Luminescence)
A luminous material applied to hands and markers for visibility in low-light or dark conditions.
Mainplate
The movement's foundational structure supporting bridges, gears, and other internal mechanical components.
Mainspring
A coiled spring storing energy that powers a mechanical watch after winding or rotor movement.
Manual Wind
A watch requiring periodic winding by hand to maintain energy and continue operating accurately.
Mineral Crystal
A hardened glass crystal offering improved scratch resistance compared to acrylic but less than sapphire.
Minute Repeater
A highly complex complication chiming hours, quarters, and minutes on demand through miniature gongs.
Moonphase
A complication displaying the current phase of the moon as viewed from Earth.
Open Heart
A dial design exposing part of the movement, typically revealing the balance wheel in operation.
Oscillation
A complete back-and-forth movement of the balance wheel regulating mechanical watch timing.
Perpetual Calendar
A calendar complication automatically accounting for varying month lengths and leap years without manual adjustment.
Power Reserve
The amount of running time available after a watch has been fully wound.
Power Reserve Indicator
A display showing the remaining stored energy before the movement requires winding.
Pushers
Buttons located on the case used to operate chronographs and other complications.
Quartz Movement
A battery-powered movement regulated by a vibrating quartz crystal, known for excellent accuracy and reliability.
Rehaut
The inner ring between dial and crystal, often featuring minute markers, branding, or decorative finishing.
Regulator
A mechanism used to fine-tune a movement's timing rate and improve accuracy.
Reserve de Marche
French term for power reserve, indicating remaining stored energy available to operate the watch.
Rotor
A weighted component in automatic movements that rotates with wrist motion to wind the mainspring.
Sapphire Crystal
An extremely scratch-resistant synthetic crystal widely used in modern luxury and premium watches.
Screw-Down Crown
A crown that threads into the case, enhancing water resistance and protecting against accidental adjustment.
Seconds Hand
The hand indicating seconds, usually rotating continuously or in discrete intervals depending on movement type.
Skeleton Watch
A watch with extensively removed material exposing internal movement components while maintaining structural functionality.
Small Seconds
A dedicated subdial displaying seconds separately from the central hour and minute hands.
Spring Bar
A spring-loaded metal pin securing straps or bracelets between the lugs.
Subdial
A smaller dial displaying additional information such as seconds, chronograph counters, or calendar functions.
Sunburst Dial
A dial finish reflecting light in radial patterns, creating dynamic visual effects as viewing angles change.
Super-LumiNova
A modern non-radioactive luminous compound commonly used for long-lasting low-light readability.
Tachymeter
A scale used with a chronograph to calculate speed based on travel over a known distance.
Tourbillon
A rotating escapement assembly designed to reduce positional timing errors caused by gravity.
Titanium
A lightweight, corrosion-resistant metal valued for strength, comfort, and hypoallergenic properties.
Uni-Directional Bezel
A bezel rotating only one direction, preventing accidental extension of dive timing measurements.
Vibration Rate
The frequency at which a balance wheel oscillates, typically measured in vibrations per hour.
Water Resistance
The watch's ability to resist water intrusion under specified testing conditions and depth ratings.
World Time
A complication displaying the time across multiple global cities simultaneously using rotating indicators.
Collector & Marketplace Terms
Essential vocabulary for buying, selling, and collecting watches.
NOS (New Old Stock)
A vintage watch that was never sold or worn despite being manufactured years earlier.
Patina
Natural aging effects on dial, hands, case, or lume that many collectors consider desirable.
Full Set
A watch sold with original box, papers, manuals, accessories, and warranty documentation.
Reference Number
The manufacturer's unique identifier for a specific watch model and configuration.
Limited Edition
A watch produced in a predetermined quantity, often featuring special design elements or commemorative significance.
In-House Movement
A movement designed and manufactured primarily by the watch brand rather than sourced externally.
Homage Watch
A watch inspired by another famous design while maintaining different branding and specifications.
Microbrand
A small independent watch company producing limited runs and selling primarily through direct channels.
Service History
A record documenting maintenance, repairs, lubrication, and restoration performed throughout the watch's lifetime.
Swiss Made
A legally protected designation indicating compliance with Swiss manufacturing and assembly requirements.