maxilla

n. jaw, upper jawbone; mouth of many invertebrate animals

The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible, which is also a fusion of two halves at the mental symphysis.
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Maxilla /max·il·la/ pl. maxil´las, maxil´lae [L.] the irregularly shaped bone that with its fellow forms the upper jaw. max´illary max·il·la n. pl. [more]Maxilla - Community and Resources

Noun
1. the upper jawbone in vertebrates; it is fused to the cranium
(synonym) upper jaw, upper jawbone
(hypernym) jaw
(part-meronym) hard palate

(n.)
The bone, or principal bone, of the upper jaw, the bone of the lower jaw being the mandible.
  

(n.)
The bone of either the upper or the under jaw.
  

(n.)
One of the lower or outer jaws of arthropods.