- Either of a pair of bones of the human skull fusing in the midline and forming the upper jaw.
- A homologous bone of the skull in other vertebrates.
- Either of two laterally moving appendages situated behind the mandibles in insects and most other arthropods.
- In <em>anatomy</em> and <em>zoology</em>: A jaw or jaw-bone; a maxillary bone; especially, a bone of the upper jaw, as distinguished from the mandible.
- Specifically, the supramaxillary bone proper, as distinguished from the premaxillary or intermaxillary, which is often fused therewith in the higher vertebrates.
- In <em>entomology</em>, as in insects and arachnidans, one of the second pair of gnathites; either one, right and left, of the second or lower pair of horizontal jaws, next behind or below the mandibles.
- In <em>Crustacea</em>, the right or left one of either of the two pairs of gnathites which come next after the mandibles, between these and the maxillipeds. The maxillæ of a crustacean thus correspond to those of an insect, but there is an additional pair of them.
- The bone of either the upper or the under jaw.
- The bone, or principal bone, of the upper jaw, the bone of the lower jaw being the <ex>mandible</ex>.
- One of the lower or outer jaws of arthropods.
- Either of the two <xref>bones</xref> that together form the upper <xref>jaw</xref>.
- <xref>Arachnid</xref> <xref>mouthpart</xref>
- the jaw in vertebrates that is fused to the cranium