English

subtriangle

From sub- + triangle.

Proto-Indo-European *upó ‘up; from below’

Proto-Italic *supo ‘under’

Latin sub ‘under, beneath, below’

English sub-

Latin triangulus ‘three-cornered, having three angles’

Latin triangulum

Old French triangle

Middle English triangle

Today it means

noun A triangle forming part of a larger triangle.

Language periods are conventional ranges, not dates for this word.

Etymograph / subtriangle