Direct Opposite of one-sided
Indirect Opposite of one-sided
nonpartisan, symmetrical, impartial, tetramerous, bipartite, four-party, three-way, nonpartizan, symmetric, fair, quadripartite, three-party, four-sided, tripartite, trilateral, two-way, three-cornered, two-party, multipartite, triangular, joint, double-faced, quadrilateral, three-sided,