Lustrums

Part of speech: noun

Definitions

1. A five-year period, particularly relevant for cycles of renewal or significant events in ancient Rome
2. A span of five years, often used in historical contexts to mark cycles of time or ceremonial practices
3. A term signifying a five-year interval, especially used in reference to periods of reflection and change in certain traditions

Etymology: The word "lustrum" has a surprisingly concrete origin: it named a Roman ceremony of purification, and the five-year span came from the calendar of that ritual. Every five years, the censors (the Roman officials who counted citizens and their property for taxation and military service) closed the census with a sacrifice that purified the entire population. The Latin "lūstrum" originally meant the purificatory rite itself, and the time between one such rite and the next became the name of the period. The plural "lustrums" is the form of that English noun, borrowed directly from Latin, where "lūstrum" is the source of the modern term. Its reliance on a ritual calendar explains why the five-year sense is the only meaning English has kept.