lustrum
                                                    英 ['lʌstrəm]
                                                                    美 ['lʌstrəm]
                        
                
                
                
                
                    
                                                                                                        lustrum 英文词源
                
                
                    
                        - 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."