merger

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The act or an instance of merging.
• noun An absorption of one corporation by another, with the corporation being absorbed losing its separate identity and governance.
• noun Law An absorption of a lesser estate, contract, criminal offense, right, or liability into a succeeding larger one, resulting in the extinction of the former.

from The Century Dictionary.

• noun One who or that which merges.
• noun A merging of the interests and control of two or more corporations, engaged in the same line, or in allied lines, of business, into a single corporation which exchanges its stock for that of the merging corporations, which however preserve, nominally at least, their separate identity.
• noun In the law of conveyancing, the sinking or obliteration of a lesser estate in lands, etc., resulting when it is transferred without qualification to the owner of a greater estate in the same property (or the like transfer of the greater estate to the owner of the lesser), if there be no intermediate estate.
• noun In the law of contracts, the extinguishment of a security for a debt by the creditor's acceptance of a higher security, such as a bond in lieu of a note, or a judgment in lieu of either: so called because such acceptance, by operation of law, and without intention of the parties, merges the lower security.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who, or that which, merges.
• noun (Law) An absorption of one estate, or one contract, in another, or of a minor offense in a greater.
• noun 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.
• noun (Business, Finance) The combining of two commercial enterprises into a unified single enterprise under a single management, with voluntary participation by both parties. Compare acquisition and takeover.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The act or process of merging two or more parts into a single unit.
• noun economics The legal union of two or more corporations into a single entity, typically assets and liabilities being assumed by the buying party.
• noun law An absorption of one or more estate(s) or contract(s) into one other, all being held by the same owner; of several counts of accusation into one judgement, etc.
• noun linguistics A type of sound change where two or more sounds merge into one.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the combination of two or more commercial companies
• noun an occurrence that involves the production of a union