leap day

Definition

An extra day intercalated into a year, especially the day intercalated into the Julian calendar every fourth year and into the Gregorian calendar every fourth year excepting centuries not divisible by 400, usually reckoned as February 29th.

Etymology

See leap year.

Example Sentences

• "This yere leapt, and the leap day was the morrow after the feast Terminalia."
• "The lunar cycle among the Chaldeans was called the saros and sara, from סהרא, sahara, the moon. This cycle it is said contained two hundred and twenty-three synodical months, or eighteen Julian years, ten days, when the same cycle or period contains five leap days, and eleven days when it contains four leap days, seven hours, forty-eight minutes, and one-fourth; in which time all the corresponding new and full moons and eclipses return again."
• "We observe then, with respect to the Julian cycle of leap-year, that, though we speak of it commonly as the cycle of the leap-year, it is in reality only the cycle of the leap-day. And this distinction is of much importance, especially to the present question. For the cycle of leap-year according to the Julian rule is one of four years, because the cycle of the leap-day in the Julian calendar is one of four also."