multilateral
mul-ti-lat-er-al
adjective
Involving three or more countries or groups in an agreement or action.
"They signed a multilateral trade deal."
Thesaurus
Synonyms: many-lobed, three-party, quadripartite, eight-sided, triangular, four-sided, three-sided, twelve-sided, four-lobed, three-lobed, three-cornered, quadrilateral
Antonyms: one-sided, unilateral