Cosignitary \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. [1913 Webster]
Cosignitary \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. [1913 Webster]