Merger
Two companies combining into one legal entity.
In a merger, two companies combine so that one legal entity survives. The distinction from an acquisition is largely presentational: most transactions described as mergers of equals leave one side's management and headquarters in charge.
A reverse triangular merger is the usual structure for buying a listed company. The buyer creates a subsidiary, merges it into the target, and the target survives as a wholly owned subsidiary of the buyer. It appears in filings as an obscure entity name that exists only for the transaction.