Acrylic Crystal: Sometimes referred to as Hesolite, an acrylic crystal is basically plastic. Polymethylacrylate is often used. Benefits of an acrylic crystal are that is flexes rather than shatters on impact, it doesn't produce too much glare under bright light and it can be polished easily.
Alarm: Alarm functions may be fitted (most commonly) to battery powered quartz watches; the alarm with beep at the pre-set time. There are mechanical alarm watches featuring a hammer which produces the alarm sound at the pre-set time. Most noteworthy examples are perhaps the Revue Thommen (and Vulcain) Cricket, the Jaeger LeCoultre Memovox and Seiko Bell-Matic.
Amplitude: Amplitude, in the case of mechanical watches refers to how many times an hour the watch goes tick for a given time period! It is often referred to as half-swings per hour or beats per hour (BPH). Thus a watch beating at an amplitude of 28,800 per hour ticks 8 times per second. Hi-beat movements running at 36,000 BPH, such as the Zenith El Primero can measure time in one tenths of a second.
Analogue: Analogue simply refers to the means of showing the time on a watch dial by means of hands which point to the hours, minutes and usually seconds.
Anchor: The anchor, sometimes referred to as Swiss anchor helps perform the final part of the mechanical process in a mechanical watch in order to divide the seconds and provide accurate timekeeping. Moving side to side, the anchor allows the final wheel (escape wheel) to rotate one cog at a time. This process produces the ticking sound of a mechanical watch.
Automatic: Automatic or automatic watches usually refers to those mechanical watches which wind themselves by means of a swinging mass or rotor (which rotates by arm movement) which through a series of gears, winds the mainspring which in turn powers the watch.
Battery EOL: Battery End Of Life indicator. This function forewarns of impending battery failure in a quartz watch by means of the second hand jumping in two or sometimes four second intervals. The wearer usually has approximately two weeks before battery failure.
Bezel: The bezel is the topmost ring of the watch, surrounding the dial of the watch. A bezel may be fixed or in the case of a diver's watch, rotating. It can either be plain (usually fixed) or can be marked with, for example a 0-60 minute scale in the case of divers' watches. Older rotating bezels were usually bi-directional, modern diving watches are equipped with a unidirectional bezel.
Blued Screws: Traditionally, high quality movements were fitted with screws which were artificially blued, more for decoration than function.
Calendar: The calendar mechanism or function on a watch can consist of a date only showing in a window through to a triple calendar, showing the date, day and month. A combination of dial cut outs and pointer hands may be used. The most complicated calendar mechanisms may be mechanically programmed to show the year, and months including those with less that 31 days; leap years can also be mechanically allowed for. Sometimes referred to as perpetual calendars.
Chronograph: A chronograph is a mechanism for measuring short time spans independently of the normal timekeeping function. Many mechanical chronographs measure up to 12 hours with indicators for seconds, minutes (usually to 30) and hours.
Chronometer: Movements which meet specific timekeeping criteria laid down by the Swiss Official Chronometer Control are awarded a Chronometer Certificate. Movements are usually tested out of the case for 15 days and nights in various positions and at various temperatures.
Crown: The crown, often referred to as the winding crown or winder is used for winding the watch in the case of a non-automatic, for setting the hands to the correct time and often for setting the date in the case of calendar equipped watches. On diving/sports models, the crown may be screw down whereby it screws onto a threaded tube which protrudes from the case of the watch. This often ensures superior water resistance.
Crystal: The crystal is the clear cover over the dial. Can be referred to as the glass. Various materials have been used over the years including acrylic, mineral (glass) and sapphire.
Decorated Movement: Some watch movements come highly decorated, for example with Geneva Stripes and blued screws. Whilst decoration may not improve function, it often indicates a degree of hand assembly/finishing and an attention to detail in the construction of a watch. Some watches show off the decorated movement through the use of a display back.
Dial: The dial, often referred to as the face is usually marked with numbers or batons to which the hands point in order for the wearer to tell the correct time. Dials themselves can be very simple, sometimes with no markers at all or extremely complex as in the case of pilots' chronographs. Dials can be decorated with patterns or in some cases with precious stones.
Digital Display: As opposed to an analogue display, a digital display shows the time in numbers. Most often used with LCD displays in the case of a quartz watch, during the 1960's there were many mechanical digitals with rotating discs instead of hands. Cut outs in the dial would show the correct time. The first quartz digital watches came onto the market in the early/mid 1970s; for example the Pulsar Time Computer.
Diver's Watch: Divers' watches traditionally are large, featuring a graduated rotating bezel and often a screw down winding crown. Water resistant to 200m as a minimum, the modern diver's watch must confirm to certain standards laid down for example by ISA in order to be classified as a Scuba Divers Watch.
Ebauche: The ebauche refers to the basic movement. To this, a particular manufacturer may add complications, decorate the movement or refine the movement by adding higher grade components.
Escapement: The escapement in a mechanical watch refers to a combination of parts including the anchor, pallets and balance wheel amongst others which translate the power of the mechanism into regular timekeeping. The escapement is responsible for the familiar ticking sound of a mechanical watch.
Flyback: This phrase is often used to describe two different functions of a chronograph watch. Some use it to describe the function of depressing a chronograph button which returns the seconds hand to zero but immediately starts the timing again. Also (probably wrongly) used to describe the split seconds chronograph which has two seconds hands sitting atop one another. On depression of a third chronograph button (most have two), the flyback hand will stop in order to measure say, a lap time; repressing this button with cause the flyback hand to flyback(!) to the other seconds hand which has remained in motion.
Gear Train: The gears used in a mechanical watch which run from the mainspring which powers the watch through to the escapement which translates that power into timekeeping.
Geneva Stripes: A form of decoration in higher grade watch movements which look like stripes on the movement plates. These used to be applied by hand; in many cases in modern times, they are very simply applied by machine.
Guilloche: A form of decoration for watch dials, giving the dial great depth. Often applied to silver or silvered dials.
Handwind/Handwound: Simply describes a watch with a mechanical movement which needs to be wound by the wearer using the winding crown. This winds the mainspring up which then releases its energy to power the watch.
Hack/Hacking: Describes the feature of a movement whereby the seconds hand can be stopped for exact setting of the time. Originally a military term for this feature.
Incabloc: Incabloc is a trade name for a type of shock absorbing device/spring used to protect the delicate parts of the mechanical watch escapement. Mentioned here as it is probably the most widely used and some watch manufacturers used to draw attention to it by referring to it on the watch dial itself.
Index/Indices: Usually refers to the markings on the dial of a watch showing hours and minutes. Can however refer to the markings on the regulator of a watch movement to aid precision adjustment for accurate timekeeping.
Jewels: In the mechanical watch and some quartz watches, jewels (usually made from synthetic ruby) are used as bearings for those parts of the movement subject to constant motion. They are not valuable at all in the monetary sense but they are valuable in aiding the precise running of a watch over a long period and reducing wear. It is a fallacy that the more jewels the better the watch. A basic handwound mechanical usually comprises 17 jewels which in the main is the optimum count. Automatics may require more for the winding mechanism itself. In the 1960s there appeared to be a competition to see who could fit the most jewels in a watch movement, manufacturers proudly referred to 100 Jewels on the dial; opening the watch usually revealed that up to 80% of these jewels had no purpose and were simply mounted here and there on the movement to up the jewel count!
Jumping Hour: System of timekeeping whereby the seconds and minutes are shown by traditional hands but the hour is shown in a dial cutout (often at 12), on the minutes hand reaching 59 minutes, the hour disc under the dial will jump to the next hour.
Kif: A trade name for a shock absorbing system; in a similar vein to Incabloc above.
LCD Display: Or Liquid Crystal Display; used for the display on most modern digital watches. Followed from the earlier LED or Light Emitting Diode display of the first quartz digital watches. The LCD was preferred as it used vastly less power than the LED thus the time could be shown constantly as opposed to having to press a button for time display.
Lugs: Protrusions on the case of a watch to which the bracelet or strap is fitted. Various types of lugs can be found such as rounded lugs, teardrop lugs and hidden lugs.
Movement: Simply used to describe the workings or engine(!) of a watch, be it mechanical or quartz. Often referred to as a calibre by manufacturers.
Mineral Crystal: Watch crystal made from what is essentially a form of glass. More scratch resistant than acrylic, a mineral crystal will however scratch and is extremely difficult to polish.
Nivarox/Nivaflex: Trade names for the metal alloy used for many Swiss watch mainsprings and hairsprings. These materials self compensate for the effects of temperature (e.g. expansion and contraction), are extremely strong and corrosion resistant.
O-Ring: O rings are used to seal the backs of watches which feature either a press-in back or a screw on back. They ensure water resistance. Usually also used on the winding stems of watches and in the winding crowns to protect against the ingestion of water and dust. Normally made from a rubber/plastic compound.
Power Reserve: In its purest sense, used to refer to how long a watch will run once fully wound. Thus a watch with a power reserve of 48 hours should run for that period. Often used to describe a watch which has a power reserve indicator on the dial (usually a small pointer hand and a relevant scale).
Quartz: Used to describe a watch powered by an oscillating quartz crystal which draws its power from a small battery. Oscillating 32,768 times per second, an electronic circuit divides this oscillation into precise increments of 1 second or less. Used in both digital and analogue watches. Whilst derided by many purists as disposable and of little soul, the quartz watch is nonetheless extremely accurate. Watches have been made super-accurate by using a much higher frequency (e.g. 4.2 million cycles per second) or by using two oscillators and by using temperature compensation.
Rattrapante: used to describe the split seconds chronograph (see Flyback) which has two seconds hands sitting atop one another. On depression of a third chronograph button (most have two), the flyback hand will stop in order to measure say, a lap time; repressing this button with cause the flyback hand to flyback(!) to the other seconds hand which has remained in motion.
Register: Another name for a sub-dial; this is usually a dial within the main dial of a watch. The best example is possibly a chronograph where there may be registers for the chronograph minutes and hours. Some watches have registers with pointers showing the day and date.
Retrograde: Used to describe a pointer hand on a watch dial (often a sub-dial) which returns to zero at the end of a prescribed period. For example a watch may have retrograde date - in this case the hand moves up a scale a day at a time, pointing to the current date - when it reaches 31 it will spring back to 1
Rotor: The oscillating mass which winds an automatic movement. A rotor most commonly is free to rotate in a full 360 degrees and may wind the watch when it is rotating in one direction only or indeed may wind in both directions through the use of reverser wheels and gears.
Sapphire Crystal: Synthetic sapphire formed for use as the crystal of a watch. Extremely scratch resistant (9 on the Moh scale), a sapphire crystal is the material of choice for many watch collectors. The downsides are that sapphire can chip at the edges if they protrude and can shatter.
Screw Crown: A watch winding crown which screws tightly to the case of the watch on a tube; the purpose is to ensure extreme water resistancy.
Shock-Resist: Describes a watch that has certain components of the movement protected by shock absorbing devices. Most often the escapement of the movement is protected by such, more specifically the balance staff.
Sub-Dial: See Register above; a dial within or on the main dial of a watch.
Tachymeter: A scale used to measure units per hour. Commonly found on the bezels of chronograph watches, an event is timed by using the chronograph seconds hand. The hand is stopped when the event ends and the hand will point to the number of units per hour that could be achieved.
Tourbillon: A complex piece of micro-engineering which results in the escapement of a watch rotating on its own axis; the object of the exercise is to cancel out the variations in running regularity which can be caused by the watch being in different positions; (a watch may gain in one position yet lose in another).
Tritium: An isotope of hydrogen used in the luminous compounds which give watch dials and hands their glow in the dark capabilities. Many watch dials will show a small T at the bottom, indicating the use of tritium. The half life of tritium is 12.5 years thus it will lose its ability to provide illumination as time passes. Now largely superceded by non-radioactive organic compounds such as the trade name Luminova.
UTC: Universal Time Co-ordinated. A universal time based on the Greenwich Meridian used by the military and in aviation. Greenwich Mean Time (GMT) can be considered approximately equivalent to Universal Time Co-ordinated(UTC).. GMT as such is now obsolete however, being replaced by UTC. Using this timezone/standard avoids errors and problems associated with different timezones and summer times operational in different countries.
Water Resist/WR: Watches have varying degrees of water resistancy, ranging from WR30 Meters to some specialist watches having a capability of withstanding water to 10000 Meters. The usual for a diver's watch is 200m whilst 100m would be suitable for everyday swimming.
Winder/Winding Crown: Same as Crown, above. Used for winding the watch and setting time/date.
X-Ray Vision: What you need these days to detect some of the counterfeit Rolex watches in circulation. Be careful!
Zulu Time: Yet another reference to GMT and UTC! The use of this phrase is prevalent in civil aviation and military. Why Zulu? Well, Zulu is the phonetic for Z and the Z is for the Zero meridian, being that meridian passing through Greenwich.