a person or thing closely resembling another, esp. in function

Our president is the counterpart of your prime minister.

a copy; duplicate.

Law . a duplicate or copy of an indenture.

one of two parts that fit, complete, or complement one another.

noun

opposite

noun

analogue , carbon copy * , complement , copy , correlate , correlative , correspondent , dead ringer * , ditto * , doppelganger , duplicate , equal , equivalent , fellow , like , look alike , mate , obverse , opposite , opposite number , peas in a pod , pendant , ringer , spit and image , spitting image * , supplement , tally , twin , two of a kind , carbon copy , facsimile , image , likeness , reduplication , replica , replication , reproduction , simulacrum , vis--vis , congener , match , companion , double , analog , carbon , parallel