maxilla

‖n.; pl. Maxillae [ L., dim. of mala jaw, jawbone. ] 1. (Anat.) (a) The bone of either the upper or the under jaw. (b) The bone, or principal bone, of the upper jaw, the bone of the lower jaw being the mandible. [ Now commonly used in this restricted sense. ] [ 1913 Webster ]

2. (Zool.) One of the lower or outer jaws of arthropods. [ 1913 Webster ]

☞ There are usually two pairs in Crustacea and one pair in insects. In certain insects they are not used as jaws, but may form suctorial organs. See Illust. under Lepidoptera, and Diptera. [ 1913 Webster ]