From The Collaborative International Dictionary of English v.0.48:

merge \merge\ (m[~e]rj), v. t. [imp. & p. p. Merged
   (m[~e]rjd); p. pr. & vb. n. Merging (m[~e]r"j[i^]ng).] [L.
   mergere, mersum. Cf. Emerge, Immerse, Marrow.]
   To cause to be swallowed up; to immerse; to sink; to absorb.
   [1913 Webster]

         To merge all natural . . . sentiment in inordinate
         vanity.                                  --Burke.
   [1913 Webster]

         Whig and Tory were merged and swallowed up in the
         transcendent duties of patriots.         --De Quincey.
   [1913 Webster]

From The Collaborative International Dictionary of English v.0.48:

merging \merging\ adj.
   1. combining or mixing.

   Syn: blending, mingling.
        [WordNet 1.5]

   2. flowing together. [prenominal]

   Syn: confluent.
        [WordNet 1.5 +PJC]

From The Collaborative International Dictionary of English v.0.48:

merging \merging\ n.
   1. The act or process of joining together into one entity.

   Syn: meeting, coming together.
        [WordNet 1.5]

   2. a flowing together (as of rivers).

   Syn: confluence, conflux.
        [WordNet 1.5]

From WordNet (r) 2.0:

merging
     adj 1: combining or mixing [syn: blending, mingling]
     2: flowing together [syn: confluent, merging(a)]
     n 1: the act of joining together as one; "the merging of the two
          groups occurred quickly"; "there was no meeting of
          minds" [syn: meeting, coming together]
     2: a flowing together [syn: confluence, conflux]

From Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "merging":
   acme, agglomeration, agglutination, aggregation, apex, apogee,
   articulation, associative, blending, bond, bracketing, climax,
   clustering, combination, combinative, combinatory, combining,
   communication, concatenation, concourse, concurrence, confluence,
   congeries, conglomeration, conjugation, conjunction, connection,
   convergence, copulation, corporational, coupling, culmination,
   federal, federative, fusing, gathering, hookup, incorporating,
   incorporative, intercommunication, intercourse, interlinking,
   joinder, joining, jointure, junction, knotting, liaison, linkage,
   linking, marriage, meeting, merger, pairing, peak, pinnacle,
   splice, summit, symbiosis, tie, tie-in, tie-up, unification, union,
   uniting, yoking, zenith