jaw
n. countablen. the lower part of your face that moves when you eat or talk. It holds your bottom teeth and helps you open and close your mouth.
n. the lower bony structure of the skull that supports the teeth and facilitates mastication and speech.
He dropped his jaw in surprise when he heard the news.
The dentist asked the patient to relax her jaw so he could examine the back teeth.
The fossilized remains included a remarkably well-preserved lower jaw, allowing researchers to determine the creature's diet based on the wear patterns of its molars.
From Middle English jawe/jowe (“jaw; sides of the lower face”, 14th century), the further origin of which is disputed. Either: From Anglo-Norman jowe, from Old French joe (“cheek; jaw”), from Vulgar Latin ga(v)ota (“cheek”), of uncertain further origin. ** It has been objected that the rhyming of jowe (“jaw”) with clowe (“claw”) in Middle English demonstrates that it did not have the vowel /uː/. This would be a concern if /uː/ were the vowel to expect from a borrowing of the Old French word, which it is not. Compare English paw < Middle English pawe/powe < Anglo-Norman powe < Old French poe. From Middle English chowe, from Old English ċēowe. The main difficulties with this theory are the notable lack of evidence and the late attestation of chaw (early 16th century). If it is correct, then the further origin would be Proto-West Germanic keuwā (“jaw”), whence Saterland Frisian Kiuwe, Dutch kieuw, German Keu, Käu. For the initial consonant, compare jowl as a variant of chavel/chawl. It is also conceivable that the word is a merger of two coincidentally similar sources. Gradually displaced Middle English chavel (from Old English ċeafl).
Uncertain. Attested since 1513 (as a verb and noun) in Scots. The DSL speculates that it might be related to Scots (and Northern English dialectal) jall, joll "knock, bump; toll (a bell)" via the notion of knocking "one thing against another, as waves on a rock". The EDD compares Old Norse jaga (“move to and fro”).
Often used in the singular to refer to the lower mandible, though 'jaws' (plural) refers to the entire mouth structure, especially of animals.