Source : Webster's Revised Unabridged Dictionary (1913)

Pinnule \Pin"nule\, n. [L. pinnula, dim. of pinna feather: cf.
   F. pinnule.]
   1. (Bot.) One of the small divisions of a decompound frond or
      leaf. See Illust. of {Bipinnate leaf}, under {Bipinnate}.

   2. (Zo["o]l.) Any one of a series of small, slender organs,
      or parts, when arranged in rows so as to have a plumelike
      appearance; as, a pinnule of a gorgonia; the pinnules of a
      crinoid.

Source : WordNet®

pinnule
     n : division of a usually pinnately divided leaf [syn: {pinna}]