The Collaborative International Dictionary of English v.0.48:
Three-way \Three"-way`\, a. Connected with, or serving to connect, three channels or pipes; as, a three-way cock or valve. [1913 Webster]WordNet (r) 3.0 (2006):
three-way adj 1: involving three parties or elements; "a tripartite treaty"; "a tripartite division"; "a three-way playoff" [syn: tripartite, three-party, three-way]