lustrum

lus·trum  (lstrm)

n. pl. lus·trums or lus·tra (-tr)

1. A ceremonial purification of the entire ancient Roman population after the census every five years.

2. A period of five years.

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[Latin lstrum; see luster.]

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lustrum [ˈlʌstrəm], lustre

n pl -trums, -tra [-trə]

(Mathematics & Measurements / Units) a period of five years

[from Latin: ceremony of purification, from lustrāre to brighten, purify]

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lustrum, luster, lustre

a period of five years.

See also: Calendar

Thesaurus

Noun	1.	lustrum - a period of five years period, period of time, time period - an amount of time; "a time period of 30 years"; "hastened the period of time of his recovery"; "Picasso's blue period"
	2.	lustrum - a ceremonial purification of the Roman population every five years following the census ceremony - the proper or conventional behavior on some solemn occasion; "an inaugural ceremony" capital of Italy, Eternal City, Italian capital, Rome, Roma - capital and largest city of Italy; on the Tiber; seat of the Roman Catholic Church; formerly the capital of the Roman Republic and the Roman Empire antiquity - the historic period preceding the Middle Ages in Europe