The Collaborative International Dictionary of English v.0.48:

Coalesce \Co`a*lesce"\, v. i. [imp. & p. p. Coalesced; p. pr.
   & vb. n. Coalescing.] [L. coalescere, coalitium; co- +
   alescere to grow up, incho. fr. alere to nourish. See
   Aliment, n.]
   1. To grow together; to unite by growth into one body; as,
      the parts separated by a wound coalesce.
      [1913 Webster]

   2. To unite in one body or product; to combine into one body
      or community; as, vapors coalesce.
      [1913 Webster]

            The Jews were incapable of coalescing with other
            nations.                              --Campbell.
      [1913 Webster]

            Certain combinations of ideas that, once coalescing,
            could not be shaken loose.            --De Quincey.

   Syn: See Add.
        [1913 Webster]

WordNet (r) 3.0 (2006):

coalesce
    v 1: mix together different elements; "The colors blend well"
         [syn: blend, flux, mix, conflate, commingle,
         immix, fuse, coalesce, meld, combine, merge]
    2: fuse or cause to grow together

Moby Thesaurus II by Grady Ward, 1.0:

121 Moby Thesaurus words for "coalesce":
   act in concert, act together, add, adhere, admix, affiliate, alloy,
   ally, amalgamate, assimilate, associate, band, band together,
   be in league, bemingle, blend, bracket, cleave, cling,
   club together, coact, collaborate, collude, combine, come together,
   commingle, commix, compose, compound, comprise, concert, concoct,
   concord, concur, confederate, conglomerate, conjoin, connect,
   consolidate, conspire, cooperate, do business with, embody,
   emulsify, encompass, federate, flux, fuse, get heads together,
   get together, go partners, hang together, harmonize, hash,
   hold together, homogenize, hook up, identify, immingle, immix,
   include, incorporate, integrate, interblend, interfuse, interlace,
   interlard, intermingle, intermix, intertwine, interweave, join,
   join in, join together, jumble, keep together, knead, league,
   league together, link, lump together, make common cause, make one,
   meld, melt into one, merge, mingle, mingle-mangle, mix, mix up,
   partner, play ball, pull together, put heads together,
   put together, reciprocate, reembody, relate, roll into one,
   scramble, shade into, shuffle, solidify, stand together, stick,
   stir up, syncretize, syndicate, synthesize, team up,
   throw in together, throw together, tie in, tie up, toss together,
   unify, unite, unite efforts, wed, work, work together