The Collaborative International Dictionary of English v.0.48:

Pedipalpus \Ped`i*pal"pus\, n.; pl. Pedipalpi. [NL. See Pes,
   and Palpus.] (Zool.)
   One of the second pair of mouth organs of arachnids. In some
   they are leglike, but in others, as the scorpion, they
   terminate in a claw.
   [1913 Webster]