Other forms: jaws
Your jaw is the bone that moves your mouth open and shut when you chew. The lower one hinges just in front of your ears.
Strictly there are two, since the upper jaw is fixed to the skull and only the lower one moves. Doctors call the lower one the mandible. The word carries surprise in English, since a dropped jaw means astonishment and jaw-dropping is high praise. Informally, to jaw is to talk at length. A vice or a spanner has jaws too, meaning the parts that grip.
Middle English
jowe — jaw; sides of the lower face
English, today
jaw
From Middle English jowe (“jaw; sides of the lower face”), the further origin of which is unknown. Either:
Etymology from Wiktionary, CC BY-SA