The Collaborative International Dictionary
Underjaw
Underjaw \Un"der*jaw`\, n.
The lower jaw.
--Paley.
Wiktionary
underjaw
n. the lower part of the jaw
Usage examples of "underjaw".
The long underjaw gaped open slightly, revealing rows of needlelike fangs thrusting up from purple gums.
Less than a foot from his face, a huge rubbery-lipped maw with a shovel-shaped underjaw opened with a liquidy, slurping gasp.
Together, they tumbled into outer space, Daeman hugging Caliban as fiercely as the monster was clutching Daeman, the human’s left hand pressed up against the monster’s underjaw, trying to keep those teeth away for the eight or ten seconds he thought he needed.