1. One of a pair of mouthparts in insects, crustaceans, centipedes, and millipedes. They lie behind the mandibles and their lateral movements assist in feeding. Crustaceans have two pairs of maxillae but in insects the second pair are fused together forming the labium.

2. One of a pair of large tooth-bearing bones in the upper jaw of vertebrates. In mammals they carry all the upper teeth except the incisors.