Three sided is a term used to describe an object or shape that has three sides. However, there are several synonyms for this word that can be used to express the same idea. Some of the synonyms for the term three sided include triangular, tripartite, trigonal, trifoliate, and trilateral. Each of these words can be used interchangeably to describe a shape or object with three sides. Triangular is perhaps the most commonly used synonym of three sided. It is used to describe a shape that has three straight sides and three angles. Regardless of which synonym one uses, they all convey the same meaning.