leap year

WordReference Random House Learner's Dictionary of American English © 2026

ˈleap ˌyear, n. [countable]

1. Time (in the Western calendar) a year that contains 366 days, with February 29 as an additional day;
   it occurs every four years:
   A leap year occurs in years whose last two digits are evenly divisible by four, except for years marking a century that are not divisible by 400.
2. Time a year containing an extra day in any calendar.

WordReference Random House Unabridged Dictionary of American English © 2026

leap′ year′, 

1. Time (in the Gregorian calendar) a year that contains 366 days, with February 29 as an additional day: occurring in years whose last two digits are evenly divisible by four, except for centenary years not divisible by 400.
2. Time a year containing an extra day or extra month in any calendar. Cf. common year.
• Middle English lepe yere 1350–1400

Collins Concise English Dictionary © HarperCollins Publishers::

leap year noun

1. a calendar year of 366 days, February 29 (leap day) being the additional day, that occurs every four years (those whose number is divisible by four) except for century years whose number is not divisible by 400. It offsets the difference between the length of the solar year (365.2422 days) and the calendar year of 365 days