\Coun"ter*part`\ (koun"t?r-p?rt`), n.
1. A part corresponding to another part; anything which
   answers, or corresponds, to another; a copy; a duplicate;
   a facsimile.

         In same things the laws of Normandy agreed with the
         laws of England, so that they seem to be, as it
         were, copies or counterparts one of another. --Sir
                                               M. Hale.

2. (Law) One of two corresponding copies of an instrument; a
   duplicate.

3. A person who closely resembles another.

4. 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.

         O counterpart Of our soft sex, well are you made our
         lords.                                --Dryden.