Glossary of Watch Terms

A feature which provides a sound signal at a preset time within a 12- or 24-hour period.

A device that determines altitude by responding to changes in barometric pressure.

A watch with hands (hour, minute and sometimes second) to indicate the time.

Anti-Reflective Crystal
A special treatment applied to the crystal (sapphire or mineral) that reduces light reflection to enhance the clarity of the watch crystal.

Atomic Time (A·T)
Time measured through vibrations of atoms in a metal isotope that resembles mercury. The result is extremely accurate time that radio waves can transmit.  Atomic watches and clocks can receive the signal and display the time. These radio signals are received both automatically and on-demand from 5 signal stations located in 4 regions across the world. Signal stations include: Fort Collins, Colorado, USA; Mainflingen, Frankfurt, Germany; Shangqiu, Henan, China; Fukushima, Japan; and, Kyushu, Japan.  

A mechanical watch that requires no winding. Instead, a rotor winds the mainspring every time the wearer moves his/her wrist.

Indicator of water resistance, measuring unit of static pressure. 1 bar = 10 meters.

The ring around a watch dial that holds the crystal in place.  Some bezels rotate watches have rotating bezels that can be used as a Tachymeter to measure speed over distance.

A bracelet watch features a band made of metals or ceramic, usually in links that can be added and removed for a proper fit.

A calendar watch may display one or more of: day of week, date, month, leap year and/or year.

The type of movement in a watch. A series of numbers and letters are located on the case back to indicate the exact identity of a watch movement.

The outside enclosure for the watch movement, dial and hands and/or digital display.

Case Back
The reverse side of the case which can be removed to access the inside of the watch.

A single complete unit for storage of electrical power. The power source for a watch.

Material composed of ceramic and metal. When joined together, the results are a product with the superior wear-resistance of ceramic and the toughness and flexibility of metal.

Also referred to as a stopwatch, a watch specially made to display elapsed time. A timing sequence can be started, stopped and reset by operating push buttons. In addition to registering seconds, a chronograph sometimes has minute and hour registers as well. 

An additional function on a watch that tells something other than the time or date. 

A small knob on the side of the watch case that can be used to adjust the time and date. (If your mechanical watch isn’t automatic — the crown is used to wind the watch to keep it running.)

The clear protective cover that shrouds the watch face, made from either synthetic sapphire, acrylic or glass. 

The brand name of the nylon material that is used as a strap in many of Citizen’s products. It’s a versatile fabric suited for extreme use and provides endurance and rugged durability for watches exposed to extreme conditions and is resistant to cuts, tears and scuffs.

Depth Sensor
Usually an electro-mechanical device to measure how deep a diver is under water.

Often referred to as the face of a watch.  The dial displays the time and features numerals and markings as well as the hands.

Diamond-Like Carbon (DLC)
An ion-plating treatment that provides enhanced hardness and wear resistance compared to other types of coatings. It is typically black in color.

Diver’s Watch
A specially designed watch engineered to meet the needs of scuba divers. This type of watch has enhanced structure and sealing mechanisms to guard against the entrance of moisture.

Proprietary surface-hardening technology that maintains the original brilliance and beauty of watches, improving scratch resistance.

Eco-Drive, Eco Drive
Proprietary Citizen technology that converts light into energy to power watches, making regular battery replacement unnecessary. 

Elapsed Time
A term applied to a rotating bezel usually marked in one-minute increments. Used by divers and others to measure the passage of time from a given starting point.

Exhibition Window
Refers to a transparent cover on the dial or case back that shows off the inner workings of the movement.

A complication that allows you to reset the time on the stopwatch without having to stop the chronograph. Useful for those who need to record multiple times in quick succession, like a pilot. 

A basic watch has three hands. 1.) The smaller HOUR hand marks the hours. It circles the watch once every 12 hours. 2.) The larger MINUTE hand marks the minutes. It circles the watch once every hour. 3) The SECONDS hand sweeps around the dial reading seconds.

Metal allergy-resistant watches that prevent allergic reactions through the use of special materials and surface treatments for any exterior parts (case, back cover, bezel, crown, band, etc.) that come in contact with the skin.

The markings on the dial that represent the hours. 

Ion Plating
A method by which a coating of various metals or alloys is applied to a metal case or bracelet. In the process, the molecules of metals or alloys used for plating enter the surface of the article being plated. This process allows for superior bonding and the color becomes integrated into the surface of the metal when finished.

Synthetic gemstones, usually sapphires or rubies, set in the mechanical movement to reduce friction and maintain accurate timekeeping.

Refers to watch numerals, indices and hands that absorb light and glow in the dark enabling wearer to read time because they’ve been treated with a photoluminescent material. 

Manufacture d’Horologie
A watch company that develops its parts and movements in-house vs. assembling watches from parts made by other suppliers.

Mesh Bracelet
Intertwined stainless steel loops allow for breathability and provide a flexible and snug fit to anyone’s wrist. 

*Metalized Crystal
Edge to edge domed mineral glass crystal that has a sleek, modern look. 

Mineral Crystal
A synthetic mineral crystal (MC). Three times harder and more scratch-resistant than plain glass.

The operating mode of the watch where individual features may be activated through the push of a button, rotation of the crown or a combination of both. Some examples are setting mode, calendar mode, chronograph mode, etc.

Moon Phase
A watch complication that depicts the phases of the moon as seen from Earth.

A thin slice of sea shell that displays a rainbow of colors as it is exposed to light.

The inner-working mechanism, or engine, of a watch. Sometimes referred to as caliber.

Multi-Function Watch
A practical watch with superior aesthetic appeal. Contrary to the chronograph, the features in a multi-function watch are simpler and include subdials and calendars.

N.D. Limits
The limit of safe dive time at specific depths for which No Decompression is necessary.

Perpetual Calendar
Adjusts month-end date automatically, even for leap years.

Power Reserve
The amount of energy the watch has before it stops running.

Power Reserve Indicator
A small gauge on the dial that measures how much longer the watch can run before needing to be charged.

Radio Controlled
Technology that captures a standard time signal from a radio tower and automatically sets the time and date.

Sapphire Crystal
The clear covering of the watch dial, made of synthetic sapphire. Scratch resistant. Higher quality crystal. 

Satellite Wave GPS
Technology that receives position data and time signals from GPS satellites orbiting the Earth at 20,000 km to automatically set the correct time and date on the watch.

Screw-Down Crown
A crown used on many high-grade water-resistant watches, including diver’s watches, for a positive seal between case and crown to prevent water and dust particles from entering.

Stainless Steel
An alloy of iron with chromium and some other metals combined to make a product that is resistant to rust and ordinary corrosion, making it the metal of preference for use in watch cases and bracelets.

A watch band traditionally made of material such as leather, canvas, rubber, polyurethane, plastic or nylon with buckle a closure.

Sub Dial
A smaller dial or dials within the dial with an indicator hand for showing additional time-related information.

Super Titanium™
By treating Citizen’s proprietary surface hardening technology, Duratect, to crafted solid titanium, we created Super Titanium™. The result is a material 5 times harder and 40% lighter than stainless steel. 

An extra dial ring usually marked with numerals from 60 at the twelve position, increasing counter-clockwise around the dial up to the number 500. The tachymeter is usually found on chronograph watches. Its purpose is to give vehicles an average speed in miles or kilometers per hour over a measured course of 1 mile or 1 kilometer without taking the time for calculation.

A lustrous metal with a silver-gray appearance often used in the aerospace and marine industry. 30% stronger and 40% lighter than steel, and also hypoallergenic, Titanium is an increasingly popular watch material. Its rust and salt-water corrosion-resistance make it particularly useful in diver's watches. 

Vegan Leather
Material that simulates leather, but is composed of synthetic substance.

Water Resistant (WR)
Refers to watches that can withstand different levels of water exposure without any damage or compromise to the watch itself.  Compare your timepiece against the chart below to ensure its water-resistant characteristics.