Multangular and Trilateral

(a.) Having many angles.

noun

• A three-sided polygon.
  • synonyms: triangle, trigon

adjective

• Involving three parties.
  • usage: "trilateral talks"
• Having three sides.
  • usage: "a trilateral figure"
  • synonyms: triangular, three-sided

(a.) Having three sides; being three-sided; as, a trilateral triangle.