Source : Webster's Revised Unabridged Dictionary (1913)

Quaternate \Qua*ter"nate\, a.
   Composed of, or arranged in, sets of four; quaternary; as,
   quaternate leaves.

Source : WordNet®

quaternate
     adj : consisting of or especially arranged in sets of four;
           "quaternate leaves"; "a quaternary compound" [syn: {quaternary}]