The Collaborative International Dictionary of English v.0.48:

Transmutation \Trans`mu*ta"tion\, n. [F. transmutation, L.
   transmutatio. See Transmute.]
   1. The act of transmuting, or the state of being transmuted;
      as, the transmutation of metals.
      [1913 Webster]

   2. (Geom.) The change or reduction of one figure or body into
      another of the same area or solidity, but of a different
      form, as of a triangle into a square. [R.]
      [1913 Webster]

   3. (Biol.) The change of one species into another, which is
      assumed to take place in any development theory of life;
      transformism. --Bacon.
      [1913 Webster]

   Transmutation of metals (Alchem.), the conversion of base
      metals into gold or silver, a process often attempted by
      the alchemists. See Alchemy, and Philosopher's stone,
      under Philosopher.
      [1913 Webster]

WordNet (r) 3.0 (2006):

transmutation
    n 1: an act that changes the form or character or substance of
         something [syn: transmutation, transubstantiation]
    2: a qualitative change [syn: transformation, transmutation,
       shift]
    3: (physics) the change of one chemical element into another (as
       by nuclear decay or radioactive bombardment); "the
       transmutation of base metals into gold proved to be
       impossible"