Vicennials

Part of speech: noun

Definitions

1. Relating to events occurring every twenty years
2. Describing a cycle or pattern that recurs bi-decadally
3. Characterizing activities or phenomena that take place once in a generation span of two decades

Etymology: "Vicennials" is the plural of "vicennial," an adjective meaning recurring every twenty years. The adjective is built from Latin "vicennium," a twenty-year span, which itself comes from "vicennis," meaning "twenty-year," and ultimately from "vīciēs annus," literally "twenty times a year," with the Latin "vicies" meaning "twenty times." The construction is transparent: the "vice-" element carries the sense of twenty, and "-ennial" carries the sense of years, so the whole word is a compact way of saying "happening once per twenty-year period." Because the word is a formal coinage built from Latin parts rather than a term with a long popular history, its interest lies mainly in how neatly its pieces fit together. The suffix "-al" turns the noun "vicennium" into an adjective, which is why the plural form "vicennials" is used for things that come in such cycles.