Merger (?), n.
1. One who, or that which, merges.
[1913 Webster]
2. (Law) An absorption of one estate, or one contract, in another, or of a minor offense in a greater.
[1913 Webster]
3. The combining of two groups into a unified single group under a single leadership, with voluntary participation by the leaders or management of both groups.
[PJC]
4. Specifically: (Business, Finance) The combining of two commercial enterprises into a unified single enterprise under a single management, with voluntary participation by both parties; as, “the merger of Daimler-Benz and Chrysler into Daimler-Chrysler created a powerful competitor in the automobile manufacturing industry”. Compare acquisition and takeover.
[PJC]