noun

• (anatomy, zootomy) Synonym of jaw.
• An upper jaw especially of humans and other mammals in which the bony elements are closely fused.
• (anatomy) Either of the two bones that lie with one on each side of the upper jaw lateral to the premaxilla and that in higher vertebrates bear most of the teeth.
• (zootomy) One of the first or second pair of mouthparts posterior to the mandibles in many arthropods that are used for tasting and manipulating food.