Complication

A complication is, in ordinary trade use, any function a watch performs beyond telling the time. The word is everywhere. A citable definition is not.

What was checked and came back empty: The Seiko Museum Ginza's knowledge base, the Musée international d'horlogerie, the Science Museum Group including the Clockmakers' Museum, Royal Museums Greenwich, the Deutsches Uhrenmuseum, the Smithsonian, and the public pages of the British Horological Institute and the Antiquarian Horological Society. The term is also absent as a headword from the horological glossary hosted by the NAWCC.

What exists but is not usable here. Individual manufacturers publish their own operational tests of what counts as a complication, and the Fondation de la Haute Horlogerie publishes an entry. Neither route can carry a general definition on this Codex: a manufacturer is a Tier 1 source for its own technology, and "complication" is a general term of art rather than any one company's; the Fondation is an industry foundation and is not on the approved source list. No manufacturer's wording is quoted here, because none is cited on this entry.

Why museums explain mechanisms well and vocabulary badly. A museum's job is objects. Terminology is the province of standards bodies and horological institutes, and horology's vocabulary standard, ISO 6426-2:2026, is paywalled. That is the likely route to a citable definition, along with BHI and AHS print material.