three sided

/θriːˈsaɪdɪd/
adjective
  1. Having three sides or surfaces; triangular in shape.
    • The ancient coin was a small three-sided piece of metal.
    • The three-sided prism split the light into a rainbow of colors.
    • She drew a three-sided figure on the chalkboard for the geometry lesson.
  2. Involving three parties or perspectives, especially in a discussion or conflict.
    • They negotiated a three-sided agreement between the company, the union, and the government.
    • The debate turned into a three-sided argument among the candidates.
    • The family meeting became a three-sided conversation with each person having a different opinion.
Antonyms