Lewis Short
quādrīmātus (noun M) : quadrimus
* The age of four years (post-Aug.): extra quadrimatum,Plin. 19, 11, 58, § 181: ante quadrimatum,id. 8, 45, 70, § 176: dum quadrimatum agant,Col. 7, 9, 2; 9, 1, 7.
Charlton T. Lewis, Charles Short, A Latin Dictionary