counterpart
UK: ˈkaʊntəpɑːt | US: ˈkaʊntərpɑːrt
n. a person or thing that corresponds to or has the same function as another
n. (legal) a duplicate of a legal document
n. one of two parts that complement or mirror each other
The word "counterpart" emerged in Middle English (14th century) by combining "counter-" (from Old French contre, meaning "opposite" or "against") and "part" (from Latin pars, meaning "portion"). Originally used in legal contexts to denote matching halves of an indenture (a torn document serving as proof), it later broadened to describe any complementary or corresponding entity. The logic reflects duality – one part designed to oppose or complete another.
The CEO met with her European counterpart to discuss the merger.
The treaty requires signatures from both counterparts to be valid.
The artist created a sculpture and its counterpart for the twin cities.
Each passport has a counterpart stored in the government database.
The novel’s protagonist finds her counterpart in the antagonist’s motives.