Used attributively = consisting of, or representing, two (political or other) parties.

Of, relating to, or advocating rotativism in politics. Also in extended use. Now historical.

Of, representing, or composed of members of, two (political or other) parties.

Comprising several political parties; involving members of several political parties; of, designating, or relating to a political system in which…

Politics. Consisting of or divided into more than two opposed or competing alliances, parties, factions, concepts, etc.

Of or relating to multi-partyism.

Of, representing, or composed of members of, three (political or other) parties.