And twenty-nine in each leap year

Today is 29th February, a date in the Gregorian calendar which comes around only once every four years. As the old rhyme learned by schoolchildren in order to fix the varying  lengths of the months in their heads goes: Thirty days hath September, April, June and November; All the rest have thirty-one, Except for February alone, Which has twenty-eight days clear, And twenty-nine in each leap year.

The rhyme goes back to the 15th century at least, and the term leap year is even older.

Someone born on 29th February can only celebrate their birthday on the actual day on which they were born once every four years; the plot of Gilbert and Sullivan’s comic opera The Pirates of Penzance revolves in part around the fact that the hero Frederic was born on this day and must therefore serve out his apprenticeship to the pirate band until he reaches the age of 84.

The word leap has its origins in Old English; an infrequently used alternative to leap year is the Latin-derived bissextile year. You can read a past BuzzWord article about it here.