I. (ˈ)kwä|drenēəl, nyəl sometimes (ˈ)kwȯ|- adjective
Etymology: alteration of quadriennial
1. : comprising or lasting through four years
a quadrennial period
2. : occurring once in four years or at the end of every four years
quadrennial elections
II. noun
( -s )
1. : a quadrennial period
a political organization … functions not by quadrennial but by decades and generations — W.A.White
2. : a fourth anniversary or its celebration