Words starting with bi usually involve two things, and that's the very definition of this word: things that have two parts are bipartite. It's often used (in botany, for example) to describe two-part things joined at the base, like leaves. An animal’s hoof that has two halves is bipartite. For abstract things, the word usually suggests entirely separate parts forming a single thing: bipartite agreements/rules/legislatures. If something has three parts instead of two, it's tripartite.