| Noun | 1. | polygon, polygonal shape - a closed plane figure bounded by straight sides acute triangle, acute-angled triangle - a triangle whose interior angles are all acute equiangular triangle, equilateral triangle - a three-sided regular polygon isosceles triangle - a triangle with two equal sides oblique triangle - a triangle that contains no right angle obtuse triangle, obtuse-angled triangle - a triangle that contains an obtuse interior angle right triangle, right-angled triangle - a triangle with one right angle scalene triangle - a triangle with no two sides of equal length |
| Adj. | 1. | trilateral - involving three parties; "trilateral talks" reciprocal, mutual - concerning each of two or more persons or things; especially given or done in return; "reciprocal aid"; "reciprocal trade"; "mutual respect"; "reciprocal privileges at other clubs" |
| 2. | trilateral - having three sides; "a trilateral figure"many-sided, multilateral - having many parts or sides |