adjective 1.occurring every four years: a quadrennial festival.
2.of or lasting for four years: a quadrennial period.
noun 3.an event occurring every four years, as an anniversary or its celebration.
Origin: 1640–50; earlier
quadriennial <
Latin quadrienni(
um) (see
quadrennium) +
-al1 Related forms quad·ren·ni·al·ly, adverb