Noun: lustrum lús-trum
- A period lasting five years
"The organization celebrated its fourth lustrum with a grand gala"
- (antiquity) a ceremonial purification of the Roman population every five years following the census
"The lustrum was an important event in ancient Roman society"; "The completion of each lustrum was marked by sacrifices"
Derived forms: lustrums
Type of: ceremony, period, period of time, time period, time span
Encyclopedia: Lustrum