Abbreviation Term Definition
Adj. Adjusted This refers to compensations made to the watch's movement that increased the reliability and accuracy of the watch. Adjustments could include compensations for heat and cold, isochronism, and up to six different positions. This vintage chart gives a helpful visual explanation.
Bal. Balance Weighted, rotating wheel that functions as the timekeeping device in a watch's movement.
Bezel This is the front rim of the watch's case that covers the dial and secures the crystal.
Bow The looped ring located at the pendant of a pocket watch. Used to attach a chain or fob.
Cabochon An unfaceted stone with a domed shape.
Chronograph A watch that features a movement that can be started and stopped (as a stopwatch would) to measure short time intervals. Not the same as a stopwatch, which does not tell time.
Chronometer A watch that has been tested and certified to meet particular precision standards.
Coin Silver A metal made from silver coins (higher content of silver).
Crown The winding button on a watch.
Damascene This refers to the art of producing a pattern or design on a metal surface. The movement plates of higher-grade vintage pocket watches often feature these elaborate and beautiful damascene designs. These decorative patterns are usually created via engraving but may also be made by applying an offset metallic color to the movement plates (for example, gold wavy lines on a silver-toned nickel plate). Also spelled "damaskeen".
D/S, DS Double Sunk The watch's dial has two different areas (usually a center dial and a seconds dial) that are one and two levels below the hour ring.
DWT Pennyweight The common unit of mass used by jewelers in the measurement and valuation of precious metals (gold, silver, etc.). One DWT = 1.55517384 grams. May also be abbreviated PWT or PW.
GB&B Glass Back & Bezel Watch has open face case, and both front (bezel) and back covers are glass.
GGF Green Gold Filled Metal material with a hidden middle layer of base metal surrounded by green gold layers. Also known as "rolled gold".
GJS Gold Jewel Settings The jewels in the watch movement use settings (the metal sleeve that holds the jewel in place) made of gold as opposed to a less-expensive or less-luminous material.
Hinge Back Watch has open face case, and back cover is hinged.
HB&B Hinge Back & Bezel Watch has open face case, and both front (bezel) and back covers have hinges.
HC Hunting Case Also referred to as "Hunter" Case. Watch has a hinged cover that conceals the dial, and a stem/crown positioned at 3 o'clock (as opposed to 12 o'clock).
HCM Hunting Case Movement The watch movement winds with a stem positioned at 3 o'clock as opposed to 12 o'clock. This does not necessarily indicate that the watch is in a hunting case (HC).
Isochronism An adjustment to the movement of a watch that ensured accuracy and consistent timekeeping regardless of the mainspring's state (even if the spring was fully wound or was nearly run down).
Keyd. Key Wind Watch is wound with use of key, as opposed to turning the crown.
LS Lever Set Watch has small lever by dial, usually at 2 or 5 o'clock. To set time, lever is pulled out, then crown is rotated to select time, after which lever is pushed back in to original position.
Movement The "works" of a mechanical watch (not including the dial or case).
NOS New Old Stock This refers to a product that has never been sold (and is thus "new") but that is no longer produced by the manufacturer (such as a vintage watch).
Open-Face A pocket watch case style where the dial does not have a cover, as opposed to the Hunting Case (HC) style.
Pendant The "neck" of the watch, attaching the crown and bow to the case.
Pie Pan Design A dial with a flat center section and receding beveled dial edge, the shape resembling an upside down pie pan.
Porcl. Porcelain Ceramic material often used in vintage pocket watch dials.
Railroad Grade In order to ensure the accuracy of pocket watches used by railroad employees, with the ultimate goal of preventing train accidents, the General Railroad Timepiece Standards Commission published a set of guidelines for railroad companies and watch manufacturers in 1893. These guidelines, which specified the criteria for a railroad-grade watch, were prepared by Webb C. Ball, the general time inspector of North American railroads and founder of the Ball Watch Company. To be a railroad grade watch, the following criteria must be met:
  • be 16S or 18S
  • have 17 or more jewels
  • be lever set
  • be in an open face case
  • be adjusted to 5 or more positions
  • have easily-legible Arabic dial numerals
Recessed Crown On a pocket watch case, a detail where the shoulders or pendant of the case are taller than normal and provide side guards to the crown. On a wrist watch case, a detail where the side frame has extensions around the crown.
Repeater An added complication to a mechanical watch that, upon the pressing of a button, chimes a series of tones to audibly indicate the time shown on the watch. Repeaters were designed so that the time could still be told in the absence of light or as an aid to the visually impaired.
To view a few of our repeaters in action, take a look at these YouTube videos:
RGF Rose Gold Filled Metal material with a hidden middle layer of base metal surrounded by rose gold layers. Also known as "rolled gold".
RGP Rose Gold Plate A base metal with a very thin layer of rose-toned gold deposited and bonded on the surface.
SB&B Screw Back & Bezel Watch has open face case, and both front (bezel) and back covers screw on and off.
SB&HB Screw Bezel & Hinged Back Watch has an open face case, where the front (bezel) cover screws on and off and the back cover is hinged.
Silveroid or Silverine A base metal with traces of silver.
SS Stainless Steel (when referring to the case).
S/S, SS Single Sunk (when referring to the dial) - A portion of the dial (often an additional seconds dial) is "sunk", or one level below the hour ring.
Thick and Extra-Thick Glass Crystals We consider a thick glass crystal to have a thickness between 1.5mm & 3mm, and an extra-thick glass crystal to have a thickness greater than 3mm.
Triple Signed Indication that the watch is marked with the identical company name or jeweler on the movement, dial, and case. Wrist watches can also be marked for the company on the band and the crown.
WBM White Base Metal A white or silver-toned material, being a mix of alloys, typically with a nickel base. Used for vintage watches and jewelry.
WGF White Gold Filled Metal material with a hidden middle layer of base metal surrounded by white (silver-toned) gold layers. Also known as "rolled gold".
WGP White Gold Plate A base metal with a very thin layer of white or silver-toned gold deposited and bonded on the surface.
WP Waterproof and/or water resistant Our abbreviation to indicate a waterproof case, also referred to as a water resistant case. With the exception of divers' watches and later model watches specifically designed for it, a WP case will not prevent water from entering the movement cavity of a watch if the watch is submerged but will keep water from entering the watch if it is subjected to a small amount of water, such as when you wash your hands, are outside in the rain, etc.
YBM Yellow Base Metal A yellow or gold-toned material, being a mix of alloys, typically with a brass base. Used for vintage watches and jewelry.
YGF Yellow Gold Filled Metal material with a hidden middle layer of base metal surrounded by yellow gold layers. Also known as "rolled gold".
YGP Yellow Gold Plate A base metal with a very thin layer of yellow-toned gold deposited and bonded on the surface.

More horological terminology and definitions may be found on this Illustrated Horological Glossary provided by the National Association of Watch & Clock Collectors (NAWCC).

Other helpful pages: