The Collaborative International Dictionary of English v.0.48:

Tentaculum \Ten*tac"u*lum\, n.; pl. Tentacula. [NL. See
   Tentacle.]
   1. (Zool.) A tentacle.
      [1913 Webster]

   2. (Anat.) One of the stiff hairs situated about the mouth,
      or on the face, of many animals, and supposed to be
      tactile organs; a tactile hair.
      [1913 Webster]