chelicera

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Either of the first pair of fanglike appendages near the mouth of an arachnid or a horseshoe crab, often modified for grasping and piercing.

from The Century Dictionary.

• noun One of the anterior pair of appendages of a scorpion; a short, three-jointed organ ending in a prehensile claw. See cut under scorpion.
• noun The corresponding organ in a spider, which terminates in a sharp joint folding down on the preceding one like the blade of a pocket-knife on the handle, and having at its extremity the opening of a poison-gland.
• noun Also in English form chelicere.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun zoology One of the prehensile claws found on the proboscises of chelicerates (spiders and scorpions).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun either of the first pair of fang-like appendages near the mouth of an arachnid; often modified for grasping and piercing