lustrum

[ luhs-truh m ]
/ ˈlʌs trəm /

noun, plural lus·trums, lus·tra [luhs-truh] /ˈlʌs trə/.

Also luster; especially British, lustre. a period of five years.
Roman History. a lustration or ceremonial purification of the people, performed every five years, after the taking of the census.

Origin of lustrum

1580–90; < Latin lūstrum; cf. luster1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for lustra

British Dictionary definitions for lustra

lustrum

lustre

/ (ˈlʌstrəm) /

noun plural -trums or -tra (-trə)

a period of five years

Word Origin for lustrum

C16: from Latin: ceremony of purification, from lustrāre to brighten, purify
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012