lustrum
n.
(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."
〔李〕[lustr;-umn.] n.（古罗马每五年人口普查后的）驱邪仪式 ←lustr (L lustrum)=puridication 净化