bissextus

Century Dictionary and Cyclopedia

1. n. The extra or intercalary day inserted by the Julian calendar in the month of February every fourth year, in order to make up the six hours by which (it was reckoned) the natural or solar year exceeds the common year of 365 days. This extra day was provided for by reckoning twice the sixth day before the calends (or first) of March (or the sixth day from the calends of March, both days included, reckoning backward from the succeeding month, as was the custom of the Romans), the “sixth” (or first sixth) day proper thus corresponding to February 25th, according to our reckoning, and the extra sixth, or “second sixth,” to our February 24th. Since 1662, when the Anglican liturgy was revised, the 29th day of February has been, more conveniently, regarded as the intercalated day in all English-speaking countries. In the ecclesiastical calendars of the countries of continental Europe, however, the 24th day of February is still reckoned as the bissextus or intercalary day.