The story
- Latin · derived fromtriangulāris
- Old French · derived fromtriangulaire
- Middle English · inherited fromtriangulare
- English todaytriangular
From Middle English triangulare, trianguler, triangulere, from Old French triangulaire, triangulier and Latin triangulāris. By surface analysis, tri- + -angular.
Etymology from Wiktionary, CC BY-SA 4.0.