The Collaborative International Dictionary of English v.0.48:

Barbule \Bar"bule\, n. [L. barbula, fr. barba beard.]
   [1913 Webster]
   1. A very minute barb or beard. --Booth.
      [1913 Webster]

   2. (Zool.) One of the processes along the edges of the barbs
      of a feather, by which adjacent barbs interlock. See
      Feather.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "barbule":
   antenna, barb, barbel, barrel, cat whisker, cilium, feeler,
   filament, filamentule, palp, palpus, quill, shaft, tactile cell,
   tactile corpuscle, tactile hair, tactile organ, tactile process,
   tactor, vibrissa