Co*sig"ni*ta*ry (k?-s?g"n?-t?-r?), a. [Pref. co- + sign. Cf. Signatory.] Signing some important public document with another or with others; as, a treaty violated by one of the cosignitary powers.

Co*sig"ni*ta*ry, n.; pl. Cosignitaries (-r&?;z). One who signs a treaty or public document along with others or another; as, the cosignitaries of the treaty of Berlin.