trīˈgōnəm noun
( plural trigonums -nəmz ; or trigo·na -nə)
Etymology: New Latin, from Latin, triangle — more at trigon
: trigone: as
a. or trigonum men·ta·le -ˌmen.ˈta(ˌ)lē, -tā-, -ˈtä-
[New Latin, trigone of the chin]
: a somewhat triangular enlargement of the anteromedian part of the human mandible forming the bony support of the chin
b. or trigonum ha·ben·u·lae -həˈbenyə(ˌ)lē, -ˌlī : a triangular area in the optic thalamus