The Collaborative International Dictionary
Biternate
Biternate \Bi*ter"nate\, a. [Pref. bi- + ternate.] (Bot.)
Doubly ternate, as when a petiole has three ternate leaflets.
-- Bi*ter"nate*ly, adv.
--Gray.
Wiktionary
biternate
a. (context botany English) Having ternate leaf, each division of which is itself ternate