To talk volubly, persistently, and usually inconsequentially
The bones of the mouth
A jawlike object
His hair was tied back, his jaw and chin scruffy from a couple days' growth of hair.
What is this? shouted the regimental commander, thrusting forward his jaw and pointing at a soldier in the ranks of the third company in a greatcoat of bluish cloth, which contrasted with the others.
He clamped his jaw shut.
His jaw clenched at the question.
Lisa snapped her sagging jaw shut.