TRIPARTITE
tripartite, three-party, three-way
(adjective) involving three parties or elements; “a tripartite treaty”; “a tripartite division”; “a three-way playoff”
Source: WordNet® 3.1
Etymology
Adjective
tripartite (not comparable)
In three parts.
Done by three parties (as an agreement).
Source: Wiktionary
Trip"ar*tite, a. Etym: [L. tripartitus; tri- (see Tri-) + partitus,
p. p. of partiri to part, to divide. See Part, v. i.]
1. Divided into three parts; triparted; as, a tripartite leaf.
2. Having three corresponding parts or copies; as, to make indentures
tripartite. A. Smith.
3. Made between three parties; as, a tripartite treaty.
Source: Webster’s Unabridged Dictionary 1913 Edition