Source : Webster's Revised Unabridged Dictionary (1913)

Two-way \Two"-way`\, a. (Pipe Fitting)
   Serving to connect at will one pipe or channel with either of
   two others; as, a two-way cock.

Source : WordNet®

two-way
     adj 1: supported by both sides; "a two-way treaty" [syn: {bipartisan},
             {bipartizan}, {two-party}]
     2: involving two parties or elements; "a bipartite document";
        "a two-way treaty" [syn: {bipartite}, {two-party}]
     3: operating or permitting operation in either of two opposite
        directions; "a two-way valve"; "two-way traffic"; "two-way
        streets"