biennium

The cafeteria at the 2017 Venice Biennale. This international art exhibition is held every biennium.

Borrowed from Latin biennium, from bi- (“prefix meaning ‘having two parts; occurring twice’”) (from bis (“twice”), from duis, from duo (“two”), from Proto-Indo-European *duwo, *dwóh₁ (“two”)) + annus (“year”) (ultimately from Proto-Indo-European *h₂et-no-, probably from *h₂et- (“to go”)) + -ium (“suffix forming nouns”) (ultimately from Proto-Indo-European *-yós (“suffix forming adjectives from nouns”)).

• (Received Pronunciation) IPA^(key): /bʌɪˈɛn.ɪ.əm/
• (General American) IPA^(key): /baɪˈɛn.i.əm/
• Hyphenation: bi‧enn‧i‧um

biennium (plural bienniums or biennia)

1. A period of two years.
   • 1704, Giles Strauchius [i.e., Aegidius Strauch II]; Richard Sault, transl., “Of the Lunar Cycle”, in Breviarium Chronologicum. Or A Treatise Describing the Terms and Most Celebrated Characters, Periods and Epocha’s Used in Chronology. By Giles Strachius, D.D. and Publick Professor in the University of Wittebergh. Now Done into English from the Third Edition, in Latin. By Richard Sault, F.R.S., 2nd corr. and enl. edition, London: Printed for A. Bosvile at the Dial and Bible against St. Dunstan's Church in Fleet-street, OCLC 877176655, book II (Of Chronological Characters), § 1, pages 93–94:

     The Greeks being taught by their Oracles, that their accuſtomed Sacrifices were to be offered κατά τρία, which they underſtood as if their Year were to be regulated by the Sun, and their Days and Months were to be adjuſted by the motion of the Moon; were always ſolicitous, how by certain Periods they might reduce the diſagreeing motions of the Luminaries to a Third ſomething in which they might agree: Hence in the ancient times they are ſaid to have uſed a Biennium, intercalating every other year: But fault was found with this, and 'twas ſucceeded by a Quadriennium; upon the return of which the Olympic Games were celebrated.

   • 1858, Herodotus; George Rawlinson and Henry Rawlinson, translators and editors, “The First Book, Entitled Clio”, in The History of Herodotus. A New English Version, Edited with Copious Notes and Appendices, Illustrating the History and Geography of Herodotus, from the Most Recent Sources of Information; and Embodying the Chief Results, Historical and Ethnographical, which have been Obtained in the Progress of Cuneiform and Hieroglyphical Discovery. [...] In Four Volumes, volume I, London: John Murray, Albemarle Street, OCLC 960879497, footnote 2, page 178:

     No commentator on Herodotus has succeeded in explaining the curious mistake whereby the solar year is made to average 375 days. That Herodotus knew the true solar year was not 375, but more nearly 365 days, is clear from book ii. ch. iv. It is also clear that he must be right as to the fact that the Greeks were in the habit of intercalating a month every other year. This point is confirmed by a passage in Censorinus (De Die Natal. xviii. p. 91), where it is explained that the Greek years were alternately of 12 and 13 months, and that the biennium was called "annus magnus," or τριετηρίς.

   • 2007, Digambar Bhouraskar, “Growth and Structure of EPTA [Expanded Programme of Technical Assistance]”, in United Nations Development Aid: A Study in History and Politics, New Delhi: Academic Foundation, →ISBN, page 138:

     During the bienniums 1963–64 and 1965–66, expenditure on regional and inter-regional projects also registered a substantial growth. In fact, the share of regional projects in the total programme during the bienniums 1963–64 and 1965–66 was higher than the 12 per cent deemed desirable by the TAC [Technical Assistance Committee].

   • 2014, Joel W. Paddock, “Local and State Political Parties”, in Donald P. Haider-Markel, editor, The Oxford Handbook of State and Local Government, Oxford: Oxford University Press, →ISBN, page 231:

     Although ideology is related to the propensity for a state to adopt stringent changes to campaign finance law, culture does not have a substantive effect. However, he [Christopher Witko] finds support that a scandal in the previous biennium is associated with changes to campaign finance regulation in the current biennium, in concert with the findings of [Beth] Rosenson (2005) on the adoption of legislative ethics reforms.

   • 2016, Manabu Saeki, “Ideology of Partisan Voters and Congressional Members”, in The Phantom of a Polarized America: Myths and Truths of an Ideological Divide, Albany, N.Y.: State University of New York Press, →ISBN, page 58:

     Ideology of Republican voters demonstrates a significant, if not enormous, rightward shift during this period. In contrast to Republican legislators, the conservative shifts by Republican voters betided in a few, rather than all, biennia, interrupted by other biennia with no ideological shift.

• (1-year period): See year
• (3-year period): triennium

• biennial
• biennially

• (Classical) IPA^(key): /biˈen.ni.um/, [bɪˈɛn.ni.ũ]

bi- +‎ annus +‎ -ium

biennium n (genitive bienniī or biennī); second declension

1. biennium

Second declension.

¹Found in older Latin (until the Augustan Age).

• English: biennial
• Italian: biennio
• Spanish: bienio

Regularly declined forms of biennis.

biennium

1. genitive masculine plural of biennis
2. genitive feminine plural of biennis
3. genitive neuter plural of biennis

• biennium in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• biennium in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• biennium in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition, 1883–1887)
• biennium in Gaffiot, Félix (1934) Dictionnaire Illustré Latin-Français, Hachette