Cosignitary /(kō̇*sĭg"nĭ*tā̇*ry̆)/

1. Signing some important public document with another or with others; as, a treaty violated by one of the cosignitary powers.

pl. Cosignitaries ((-rz))

1. One who signs a treaty or public document along with others or another; as, the cosignitaries of the treaty of Berlin.