The Collaborative International Dictionary of English v.0.48:

Merger \Mer"ger\, 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]

WordNet (r) 3.0 (2006):

merger
    n 1: the combination of two or more commercial companies [syn:
         amalgamation, merger, uniting]
    2: an occurrence that involves the production of a union [syn:
       fusion, merger, unification]

Moby Thesaurus II by Grady Ward, 1.0:

129 Moby Thesaurus words for "merger":
   Anschluss, addition, admixture, affiliation, agglomeration,
   agglutination, aggregation, agreement, alignment, alliance,
   alloyage, amalgamation, articulation, assimilation, association,
   blend, blending, bond, bracketing, cabal, cahoots, cartel,
   centralization, clustering, coadunation, coalescence, coalition,
   colleagueship, collegialism, collegiality, combination, combine,
   combo, comminglement, commingling, commixture, communication,
   composition, comradeship, concatenation, concourse, concurrence,
   confederacy, confederation, confluence, confraternity, congeries,
   conglomeration, conjugation, conjunction, connection,
   consolidation, conspiracy, convergence, copartnership, copartnery,
   copulation, coupling, eclecticism, ecumenism, embodiment,
   encompassment, enosis, federalization, federation, fellowship,
   fraternalism, fraternity, fraternization, freemasonry, fusing,
   fusion, gathering, hookup, identification, immixture, inclusion,
   incorporation, integration, intercommunication, intercourse,
   interfusion, interlarding, interlardment, interlinking,
   interminglement, intermingling, intermixture, joinder, joining,
   jointure, junction, junta, knotting, league, liaison, linkage,
   linking, marriage, meeting, meld, melding, mergence, merging,
   mingling, mixing, mixture, package, package deal, pairing,
   partnership, pluralism, pooling, sodality, solidification,
   sorority, splice, symbiosis, syncretism, syndication, syneresis,
   synthesis, tie, tie-in, tie-up, unification, union, wedding,
   yoking



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MERGER. Where a greater and lesser thing meet, and the latter loses its
separate existence and sinks into the former. It is applied to estates,
rights, crimes, and torts.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MERGER, estates. When a greater estate and less coincide and meet in one and
the same person, without any intermediate estate, the less is immediately
merged, that is, sunk or drowned in the latter; example, if there be a
tenant for years, and the reversion in fee simple descends to, or is
purchased by him, the term of years is merged in the inheritance, and no
longer exists; but they must be to one and the same person, at one and the
same time, in one and the same right. 2 BL Com. 177; 3 Mass. Rep. 172;
Latch, 153; Poph. 166; 1 John. Ch. R. 417; 3 John. Ch. R. 53; 6 Madd. Ch. R.
119.
     2. The estate in which the merger takes place, is not enlarged by the
accession of the preceding estate; and the greater, or only subsisting
estate, continues, after the merger, precisely of the same quantity and
extent of ownership, as it was before the accession of the estate which is
merged, and the lesser estate is extinguished. Prest. on Conv. 7. As a
general rule, equal estates will not drown in each other.
     3. The merger is produced, either from the meeting of an estate of
higher degree, with an estate of inferior degree; or from the meeting of the
particular estate and the immediate reversion, in the same person. 4 Kent,
Com. 98. Vide 3 Prest. on Conv. which is devoted to this subject. Vide,
generally, Bac. Ab. Leases, &c. R; 15 Vin. Ab. 361; Dane's Ab. Index, h.t.;
10 Verm. R. 293;; 8 Watts, R. 146; Co. Litt. 338 b, note 4; Hill. Ab. Index,
h.t.; Bouv. Inst; Index, h.t.; and Confusion; Consolidation; Unity of
Possession.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MERGER, crim. law. When a man commits a great crime which includes a lesser,
the latter is merged in the former.
     2. Murder, when committed by blows, necessarily includes an assault and
battery; a battery, an assault; a burglary, when accompanied with a
felonious taking of personal property, a larceny in all these, and similar
cases, the lesser crime is merged in the greater.
     3. But when one offence is of the same character with the other, there
is no merger; as in the case of a conspiracy to commit a misdemeanor, and
the misdemeanor is afterwards committed in pursuance of the conspiracy. The
two crimes being of equal degree, there can be no legal merger. 4 Wend. R.
265. Vide Civil Remedy.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MERGER, rights. Rights are said to be merged when the same person who is
bound to pay is also entitled to receive. This is more properly called a
confusion of rights, or extinguishment.
     2. When there is a confusion of rights, and the debtor and creditor
become the same person, there can be no right to put in execution; but there
is an immediate merger. 2 Ves. jr. 264. Example: a man becomes indebted to a
woman in a sum of money, and afterwards marries her, there is immediately a
confusion of rights, and the debt is merged or extinguished.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MERGER, torts. Where a person in committing a felony also commits a tort
against a private person; in this case, the wrong is sunk in the felony, at
least, until after the felon's conviction.
     2. The old maxim that a trespass is merged in a felony, has sometimes
been supposed to mean that there is no redress by civil action for an injury
which amounts to a felony. But it is now established that the defendant is
liable to the party injured either after his conviction; Latch, 144; Noy,
82; W. Jones, 147; Sty. 346; 1 Mod. 282; 1 Hale, P. C. 546; or acquittal. 12
East, R. 409; 1 Tayl. R. 58; 2 Hayw. 108. If the civil action be commenced
before, the plaintiff will be nonsuited. Yelv. 90, a, n. See Hamm. N. P. 63;
Kely. 48; Cas. Tempt. Hardw. 350; Lofft. 88; 2 T.R. 750; 3 Greenl. R. 458.
Butler, J., says, this doctrine is not extended beyond actions of trespass
or tort. 4 T. R. 333. See also 1 H. Bl. 583, 588, 594; 15 Mass. R. 78; Id.
336. Vide Civil Remedy; Injury.
     3. The Revised Statutes of New York, part 3, c. 4, t. 1, s. 2, direct
that the right of action of any person injured by any felony, shall not, in
any case, be merged in such felony, or be in any manner affected thereby. In
Kentucky, Pr. Dec. 203, and New Hampshire, 6 N. H. Rep. 454, the owner of
stolen goods, may immediately. pursue his civil remedy. See, generally,
Minor, 8; 1 Stew. R. 70; 15 Mass. 336; Coxe, 115; 4 Ham. 376; 4 N. Hanp.
Rep. 239; 1 Miles, R. 212; 6 Rand. 223; 1 Const. R. 231; 2 Root, 90.