The Collaborative International Dictionary
Bissextile \Bis*sex"tile\, n. [L. bissextilis annus, fr. bissextus (bis + sextus sixth, fr. sex six) the sixth of the calends of March, or twenty-fourth day of February, which was reckoned twice every fourth year, by the intercalation of a day.] Leap year; every fourth year, in which a day is added to the month of February on account of the excess of the tropical year (365 d. 5 h. 48 m. 46 s.) above 365 days. But one day added every four years is equivalent to six hours each year, which is 11 m. 14 s. more than the excess of the real year. Hence, it is necessary to suppress the bissextile day at the end of every century which is not divisible by 400, while it is retained at the end of those which are divisible by 400.
Bissextile \Bis*sex"tile\, a. Pertaining to leap year.
Douglas Harper's Etymology Dictionary
1580s (n.); 1590s (adj.), in reference to Roman leap year, from Late Latin (annus) bissextilis "leap year," literally "the twice sixth-day," because the sixth day before the Calends of March was doubled.
Wiktionary
a. Having an extra day (of a leap year). n. A leap year; A year having an extra day.
WordNet
Usage examples of "bissextile".
Its adoption upon our present Gregorian calendar would only require the suppression of the usual bissextile once in every 128 years, and there would be no necessity for any further correction, as the error is so insignificant that it would not amount to a day in 100,000 years.
Its adoption upon our present Gregorian calendar would only require the suppression of the usual bissextile once in every 128 years, and there would be no necessity for any further correction, as the error is so insignificant that it would not amount to a day in 100,000 years.