Added 9 October 2026 equilateral adjective Categories: Describing WordsRare Words adjective ! Definition from Wiktionary (CC BY-SA). More about equilateral at Wordnik → Where our words come from → Having all the sides equal. Having all the faces equal. Having the two sides equal, as a surface divisible by a longitudinal median line into two halves of the same form. noun A side exactly corresponding, or equal, to others. A figure having all its sides equal. Related Words: equalregularæquilateralequiangularequangularequiregularequifacialisoscelesequiangleequiangledisogonicequidiagonal Back to today's word