noun

• One that merges.
• The act or process of merging two or more parts into a single unit.
• (economics) The legal union of two or more corporations into a single entity, typically assets and liabilities being assumed by the buying party.
• (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.
• (phonology) A type of sound change where two or more sounds merge into one.