triangle
n.
late 14c., from Old French triangle (13c.), from Latin triangulum "triangle," noun use of neuter of adjective triangulus "three-cornered, having three angles," from tri- "three" (see tri-) + angulus "corner, angle" (see angle, n.).
〔李〕[tri-=three三；angle n.角 →] n.a plane figure having three sides and three angles三角（形）
〔李〕[tri-;angle] n.三角（形） ←angul,angl (L angulus)=angle 角