Coun'ter-pārt, n.
n. 1. A part corresponding to another part; any thing which answers, or corresponds, to another, as the two papers of a contract or indentures; a copy; a duplicate.
In some 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. Hale.
Sense 2. (Law.) One of two corresponding copies of an instrument; a duplicate.
Sense 3. A thing that 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 any thing; hence, a person or thing having qualities lacking in another; an opposite.
O counterpart Of our soft sex, well are you made our lords, So bold, so great, so godlike are you formed. Dryden.
Sense 4. (Mus.) The part to be arranged or used in connection with another; as, the bass is the counter-part to the treble.