The Collaborative International Dictionary of English v.0.48:

Chelicera \Che*lic"e*ra\ (k[-e]*l[i^]s"[-e]*r[.a]), n.; pl.
   Chelicer[ae] (-r[=e]). [NL., fr. Gr. chhlh` claw + ke`ras
   horn.] (Zool.)
   One of the anterior pair of mouth organs, terminated by a
   pincherlike claw, in scorpions and allied Arachnida. They are
   homologous with the falcers of spiders, and probably with the
   mandibles of insects.
   [1913 Webster]

WordNet (r) 3.0 (2006):

chelicera
    n 1: either of the first pair of fang-like appendages near the
         mouth of an arachnid; often modified for grasping and
         piercing