What does lustrum mean?
A lustrum is a period of five years, with its strongest historical association in the regular census cycle of ancient Rome. The Romans called each five-year census interval a lustrum, combining the administrative task of counting citizens and property with ceremonial acts of purification. The word can still be used for any five-year span, as in a sentence about a project lasting for a lustrum, but it is now uncommon in everyday English and sounds formal, historical, or literary. Its principal value is that it provides a precise and memorable term for a five-year period while also evoking the Roman practice from which the modern calendrical expression developed. “Quinquennium” is a learned synonym, but “lustrum” is more immediately associated with Rome and its famous census tradition.
nounA period of five years, especially the five-year census cycle of ancient Rome. The word is now chiefly historical or literary.
- A period of five years, especially the ancient Roman census cycle.
"The project was designed to endure for a lustrum, with its progress reviewed every five years."
"The bridge remained open throughout the lustrum, despite repeated floods."
"Each lustrum, Roman officials conducted a census of citizens and their property."
The regular plural is formed by adding “-s”.
"Several lustrums passed before the building was finally completed."
Roman censuses came every lustrum—because one lustrum was five years, and the population was checked in the name of purification.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of lustrum
The English word comes from Latin lustrum, meaning a five-year period and, more particularly, the Roman census cycle. The Latin term was associated with the ceremonies of purification performed at the census. Related English forms such as lustration and lustrate preserve the idea of cleansing or purification.
How lustrum is actually used
Rare and chiefly literary, historical, or specialized. In modern English it usually evokes the Roman census cycle, while in general prose a phrase such as “five-year period” is more natural.