Variation in rate: The gain or loss against perfect timekeeping each day. This is particularly noticeable in a mechanical watch; much less so in a quartz watch. It must fall within strict tolerance thresholds in order for the movement to be granted chronometer certification.

VHP: Very High Precision. A quartz movement with a temperature sensor to keep rate variations to within extremely narrow margins.

Vibration: Movement of a pendulum or other oscillating element, limited by two consecutive extreme positions. The balance of a mechanical watch generally makes five or six vibrations per second (i.e. 18,000 or 21,600 per hour), but that of a high-frequency watch may make seven, eight or even ten vibrations per second (i.e. 25,200 or 28,800 or 36,000 per hour).

W

Watch Material: Loose parts, components either for producing watches or for repairing them. In the latter case, they are often called "spare parts" or "repair material".

Waterproof: A term that cannot legally be used in the USA and is often misused. No watch is fully 100 percent waterproof.

Water resistance: The ability of a watch to resist moisture. A watch bearing the inscription "water-resistant" on its case back can handle light moisture, such as a rainstorm or sink splashes, but should not be worn swimming or diving. If the watch can be submerged in water, it must state at what depth it maintains water-resistance, i.e. 50 meters (165 feet) or more on most sport watches (100 meters). At 200 meters, the watch may be used for scuba diving depending upon the indicated depths. Sometimes water-resistance is measured in atmospheres (ATM), which is equal to 10 meters of water pressure. (Some European-made watches use the term "bar" instead). Straps other than metal bracelets may not be water-resistant. New water-resistant versions of nylon, rubber, and other synthetics are likely used in sport watches.
Watches come in different water resistant depths and diver's depths:
• Water resistant—Will withstand splashes of water or rain but should not be worn while swimming or diving.
• Water tested to 50 meters (165 feet)—Suitable for showering or swimming in shallow water.
• Water tested to 100 meters (330 feet)—Suitable for swimming or snorkeling.
• Water tested to 150 meters (500 feet)— Suitable for snorkeling.
• Water tested to 200 meters (660 feet)—Suitable for scuba diving.
Diver's to 150 meters—Meets ISO Standards and is suitable for skin diving.
Diver's to 200 meters—Meets ISO Standards and is suitable for scuba diving.

Wheel: Circular movement part (wheel plate + pinion) that spins around an axis and transmits force or energy.

Wheel plate: Movement part which, together with a pinion, forms a wheel.

White Gold: Created from yellow gold by incorporating either nickel or palladium to the alloy to achieve a white color. White gold is found in 10k, 14k, and 18k alloys, 9k in the case of England. The standard for most luxury production is 18k.

White On: An analog watch that is able to display digital functions at the touch of a button. An easily legible white numeric display appears on the inside surface of the crystal when any digital function is activated.

Winding: Operation consisting in tightening the mainspring of a watch.

This can be done by hand (by means of the crown) or automatically (by means of a rotor, which is caused to swing by the movements of the wearer's arm).

Winding mechanism: Part of a mechanical watch, designed for winding. The winding mechanism of manually wound movements operated by the crown, while in self-winding watches this is achieved by the rotor driven by wrist movements.

Winder: a machine designed to rotate an automatic watch in the absence of being worn, thus maintaining motion of the rotor and therefore tension in the mainspring. In rare instance (such as the specialty piece by Orbita) a manual watch may also be wound by such a device.

World timers: A watch with a dial that indicates up to 24 time zones around the world, usually found on the outer edge of the face or sometimes on the bezel. Time zones around the world are indicated by major cities.

X

XOskeleton: A boutique brand specializing in innovative concept designs melding science and art. One of only two brands in current production to use 904L steel (the other being Rolex). Known for their attention to ergonomics and distinctive patented "O ring" case design.

Y

Yellow gold: The traditionally popular gold used in all gold or gold and stainless steel or other precious metal combinations. Yellow gold watches may be found in 10k or 14k, or as found from most luxury manufacturers, 18k.

Z

Zulu Time: Refers to GMT or UTC time. Think of it as whatever time it is in Greenwich, England at the chosen moment. The use of this phrase is prevalent in civil aviation and military as it allows all personnel to share a common time no matter where they are on the globe. Zulu is the phonetic for Z and the Z is for the Zero meridian, being that meridian passing through Greenwich.