The Collaborative International Dictionary of English v.0.48:

Pinnate \Pin"nate\, Pinnated \Pin"na*ted\, a. [L. pinnatus
   feathered, fr. pinna a feather. See Pin a peg, Pen
   feather.]
   1. (Bot.) Consisting of several leaflets, or separate
      portions, arranged on each side of a common petiole, as
      the leaves of a rosebush, a hickory, or an ash. See
      Abruptly pinnate, and Illust., under Abruptly.
      [1913 Webster]

   2. (Zool.) Having a winglike tuft of long feathers on each
      side of the neck.
      [1913 Webster]

   Pinnated grouse (Zool.), the prairie chicken.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pinnate
    adj 1: (of a leaf shape) featherlike; having leaflets on each
           side of a common axis [syn: pinnate, pinnated]