triangular

adjective

tri·​an·​gu·​lar trī-ˈaŋ-gyə-lər 

1

a

: of, relating to, or having the form of a triangle

a triangular plot of land

b

: having a triangular base or principal surface

a triangular table

a triangular pyramid

2

a(1)

: of, relating to, or involving three elements

a triangular agreement

(2)

of a military group : based primarily on three units

b

: of or relating to a love triangle

triangularity

(ˌ)trī-ˌaŋ-gyə-ˈler-ə-tē 

-ˈla-rə-tē

noun

triangularly

trī-ˈaŋ-gyə-lər-lē 

adverb

Examples of triangular in a Sentence

Recent Examples on the Web

The new collection includes solid-colored one-pieces, as well as a colorful array of triangular bikini tops or Brazilian-cut briefs, tied at the sides to show even more skin. —Christian Allaire, Vogue, 21 Apr. 2026

This soft, triangular glow appears after sunset or before sunrise, stretching upward from the horizon like a celestial spotlight. —Valerie Mesa, PEOPLE, 17 Apr. 2026

The researchers found that a combination of shapes, forming triangular wavy plates, was most effective. —New Atlas, 10 Apr. 2026

The aircraft also includes a triangular wing design and a modular structure. —Sujita Sinha, Interesting Engineering, 3 Apr. 2026

Word History

Etymology

Middle English trianguler, from Late Latin triangularis, from Latin triangulum

First Known Use

14th century, in the meaning defined at sense 1a

Phrases Containing triangular

• triangular number

Rhymes for triangular

• angular
• quadrangular
• rectangular
• subangular
• subtriangular

Kids Definition

triangular

adjective

tri·​an·​gu·​lar trī-ˈaŋ-gyə-lər 

1

: of, relating to, or having the form of a triangle

2

: having a triangular base or principal surface

a triangular pyramid

Medical Definition

triangular

noun

tri·​an·​gu·​lar trī-ˈaŋ-gyə-lər 

: triquetral bone