Someone's or something's counterpart is another person or thing that has a similar function or position in a different place. The Foreign Secretary telephoned his Italian counterpart to protest. someone or something that has the same job or purpose as someone or something else in a different place sb's counterpart
A thing may be applied to another thing so as to fit perfectly, as a seal to its impression; hence, a thing which is adapted to another thing, or which supplements it; that which serves to complete or complement anything; hence, a person or thing having qualities lacking in another; an opposite
a duplicate copy a person or thing having the same function or characteristics as another