The Collaborative International Dictionary of English v.0.48:

Tridactyl \Tri*dac"tyl\ Tridactyle \Tri*dac"tyle\, a. [Gr. ?: ?
   (see Tri-) + ? digit: cf. F. tridactyle.] (Biol.)
   Having three fingers or toes, or composed of three movable
   parts attached to a common base.
   [1913 Webster]