(plural lustra), "purification of the Roman people every five years," 1580s, from Latin lustrum, perhaps from root of luere "to wash," related to lavere (see lave). Or [Watkins, Klein] from PIE *leuk-stro-, from base *leuk- "light, brightness."
英英释意
1. a period of five years
2. a ceremonial purification of the Roman population every five years following the census
