LUSTRUM was the name applied to a period of five solar years among the Romans, and the termination of this period was generally marked by great religious solemnities. A purifying sacrifice, called suovetaurilia, was usually offered at this time by one of the censors in the Campus Martins (Liv., i. 44) ; and the victims consisted of a cow, a sheep, and a bull, which were led round the people three times and then slain ; but this sacrifice was sometimes omitted on religious grounds. (Liv., iii. 22.) The first of these services was solemnised at Rome under King Servius, n.c. 566 ; • the last under Vespasian, iu A.D. 74. Varro (` De Ling. Lat.,' v. 2) derives the word lustrum from lucre, because the farmers paid their taxes at that time ; but others, with more probability, trace the*etymology to the purifying sacrifice which was then offered.
It is well known that the most ancient Roman year consisted only of 10 months, or 304 days, and that this year continued to be used for religious purposes. Niebuhr, in his History of Rome,' has shown
that the lust rum was the period after which the beginnings of the civil and religious years were made to coincide ; since five solar or civil years of 365 days each, containing 1825 days, coincide with six religious years of 304 days each, containing 1824 days, with the difference of one day.
In the time of Domitian the name of lustrum was given to the public games which were exhibited 'every fifth year in honour of the Capitoline Jupiter. (Sueton., Domitian,' c. 4.) The poets frequently used the word for any space of five years (Hor., Od.,' ii. 4,24 ; iv. 1-6), and sometimes confounded it with the Greek olympiad, which was only a space of four years. (Ovid, ' Pont.,' iv. 6-5 ; Martial, iv. 45.) (Niebuhr's History of Rome, vol. i., pp. 270-280, Eng. transl.; Creuzer's Abriss der Rbmischen Antiguittiten, p. 146 ; and the article CENSOR in this work.)