trilateral trilateral /traɪˈlætɝəl/

adjective

1. Having three sides  ( three-sided , triangular , trilateral )
   having three sides
    A trilateral figure
   a trilateral figure
   
2. Involving three parties  ( trilateral )
   involving three parties
    Trilateral talks
   trilateral talks
   

noun

1. A three-sided polygon  ( trigon , trilateral , triangle )
   a three-sided polygon
    A triangle has three sides and three angles
   A triangle has three sides and three angles