quā̆drĭennĭum, ii, n. [quadriennis],
a space or period of four years (class.), Cic. Caecin. 7, 19; id. Opt. Gen. 7, 22; id. Sen. 4, 10; id. Verr. 2, 3, 18, § 47; Flor. 2, 6.
quadriennium ī, n quattuor+annus, a period of four years : (fundum) quadriennium possedit: rettuli...
An Elementary Latin Dictionary