leap year n.

c. 1200, from Old English hleapan "to jump, spring clear of the ground by force of an initial bound; run, go; dance, leap upon (a horse)" (class VII strong verb; past tense hleop, past participle hleapen), from Proto-Germanic *hlaupanan (source also of Old Saxon hlopan, Old Norse hlaupa, Old Frisian hlapa, Dutch lopen, Old High German hlouffan, German laufen "to run," Gothic us-hlaupan "to jump up"), of uncertain origin, with no known cognates beyond Germanic; perhaps a substratum word.

First loke and aftirward lepe [proverb recorded from mid-15c.]

Transitive sense "pass over by leaping" is from early 15c. Leap-frog, the children's game, is attested by that name from 1590s ("Henry V"); figurative use by 1704; as a verb from 1872. To leap tall buildings in a single bound (1940s) is from the description of Superman's powers. Related: Leaped; leaping.

Old English gear (West Saxon), ger (Anglian) "year," from Proto-Germanic *jēr "year" (source also of Old Saxon, Old High German jar, Old Norse ar, Danish aar, Old Frisian ger, Dutch jaar, German Jahr, Gothic jer "year"), from PIE *yer-o-, from root *yer- "year, season" (source also of Avestan yare (nominative singular) "year;" Greek hōra "year, season, any part of a year," also "any part of a day, hour;" Old Church Slavonic jaru, Bohemian jaro "spring;" Latin hornus "of this year;" Old Persian dušiyaram "famine," literally "bad year"). Probably originally "that which makes [a complete cycle]," and from verbal root *ei- meaning "to do, make."

1580s (n.); 1590s (adj.), in reference to Roman leap year, from Late Latin (annus) bisextilis "leap year," more literally "the twice sixth-day, (a year) containing a second sixth (day)." To keep the Julian calendar consistent with the sun, the sixth day (by inclusive reckoning) before the Calends of March was doubled every four years. The date corresponds to our February 24th. From Latin bissextus/bisextis (dies), from bis "twice" (see bis-) + sextus "sixth (day before the First of March)," from sex "six" (see six).