cosignatory
adjective
signing jointly with another or others.
The grammatical form denoting more than one person, place, thing, or idea.
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The Europeans — as well as the cosignatories Russia and China — want Iran to continue to abide by the deal, which is considered a signal accomplishment of European diplomacy.
From New York Times ● May 15, 2018