Triangle
/ˈtraɪ.æŋ.ɡəl/noun
A plane figure with three straight sides and three angles.
Did you know?Its name comes from Latin tri- (“three”) + angulus (“corner”), and that same ancient root behind angulus also gives English words like angle, ankle, and even angina.
Etymological Timeline
Proto-Indo-European
PIE
*h₂enk-
“to bend, hook, or curve”
Latin
Latin
angulus
“corner, angle”
Latin
Latin
triangulum
“three-cornered figure; triangle”
Old French
OF
triangle
“triangle”
Middle English
English
triangle
“a geometric figure with three sides”
Modern English
English
triangle
“a plane figure with three straight sides and three angles”