— quadrennially , adv.
/kwo dren"ee euhl/ , adj.
1. occurring every four years: a quadrennial festival.
2. of or lasting for four years: a quadrennial period.
n.
3. an event occurring every four years, as an anniversary or its celebration.
[ 1640-50; earlier quadriennial quadrienni ( um ) (see QUADRENNIUM) + -AL 1 ]