The Collaborative International Dictionary of English v.0.48:
Quaternate \Qua*ter"nate\, a. Composed of, or arranged in, sets of four; quaternary; as, quaternate leaves. [1913 Webster]WordNet (r) 3.0 (2006):
quaternate adj 1: consisting of or especially arranged in sets of four; "quaternate leaves"; "a quaternary compound" [syn: quaternate, quaternary]