QUINQUENNIALLY

Etymology

Adverb

quinquennially (not comparable)

Every five years.

Source: Wiktionary

QUINQUENNIAL

Quin*quen"ni*al, a. Etym: [L. quinquennalis and quinquennis; quinque five + annus year. See Five, and cf. Biennial.]

Definition: Occurring once in five years, or at the end of every five years; also, lasting five years. A quinquennial event.

Source: Webster’s Unabridged Dictionary 1913 Edition