biennium

Definition

A period of two years, particularly for purposes involving intercalation or fiscal calculations.

Etymology

From Latin biennium, from biennis (“2-year”) + -ium (suffix forming abstract nouns), from bi- (“two”) + annus (“year”), q.v.

Example Sentences

• "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."
• "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."
• "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]."