Glossary

These are the terms that carry weight in our reviews. Each is defined here exactly as it is defined in the pop-up you get by tapping it mid-sentence — one definition, used everywhere, so a term never quietly means something different on another page.

Bayesian: A way of weighting an average by how much evidence sits behind it. A perfect 5 from four buyers is pulled towards the category's own average until enough people have voted to make it mean something; a 4.5 from four thousand is barely moved.
bezel: The ring around the crystal — decorative on dress watches, functional on sports watches, where it times dives or computes speed.
caliber: The numbered design of a movement ('Caliber 593'). Brands reuse proven calibers across models for decades, so one movement's reputation covers many watches.
case diameter: The width of the case measured without the crown — the number quoted as '40mm'. 34-39mm reads classic, 40-46mm reads modern.
category average: The mean price across every product we track in this category. Our catalogue, not the whole of the shop — which is why the figure is stated with the count it was taken from.
chronograph: A watch with stopwatch pushers and sub-dials counting elapsed minutes and hours. Not the same as a chronometer, which is an accuracy certification.
confidence score: Our own figure, 0-100, for how much weight the star rating can carry. It combines the Bayesian-adjusted rating with the number of people who left one, so a 4.8 from 30 buyers scores below a 4.5 from 4,000.
dive bezel: The unidirectional rotating ring with 60-minute markings. It turns one way only, so a knock can only make it show less remaining time, never more.
Eco-Drive: Citizen's light-powered quartz: any light recharges the cell, so there is no battery to change for decades. Casio's equivalent is Tough Solar.
hacking seconds: When pulling the crown out to set the time stops the seconds hand, letting you set the watch to the exact second against a reference clock.
ISO 6425: The standard a watch must pass (200 m pressure, luminous markings, a timing bezel) before 'DIVER'S' may be printed on the dial. A bare '200M' marking is not it.
lug-to-lug: The distance between the top and bottom strap attachments. If it overhangs the flat top of your wrist, the watch wears bigger than its diameter suggests.
lume: The glowing paint on hands and markers, charged by light; strontium-aluminate lume glows for hours after seconds of exposure.
NATO strap: A one-piece nylon strap threading through both spring bars — military origin, cheap, comfortable, instant-drying.
power reserve: How long a fully wound mechanical watch keeps running while unworn — 38-42 hours is standard. Wear it or wind it before that expires.
sapphire crystal: A dial cover of synthetic sapphire, the most scratch-resistant glass fitted to watches. Mineral glass is the cheaper middle; plastic (hesalite) is budget and shatterproof.
screw-down crown: A crown that threads into the case to seal it against water. Screw it back in after setting — an open crown is the most common way a rated watch takes on water.
spring bars: The spring-loaded pins holding the strap to the case. Quick-release spring bars add a latch, so straps swap without tools.
tachymeter: The speed scale engraved on some chronograph bezels: time a known distance and the second hand reads off your average speed.
Tough Solar: Casio's solar charging: light tops up a rechargeable cell, removing battery changes. Citizen's equivalent is Eco-Drive.
value score: Our own figure, 0-100. Half of it is where the price sits in this category's price spread, half is the Bayesian-adjusted rating. It is arithmetic on published numbers, not an opinion.
water resistance: A pressure-test rating, not a depth licence: 30M survives rain, 50M shallow swimming, 100M swimming and snorkelling, 200M high-impact water sports.