The Collaborative International Dictionary of English v.0.48:

Blossom \Blos"som\, v. i. [imp. & p. p. Blossomed; p. pr. &
   vb. n. Blossoming.] [AS. bl?stmian. See Blossom, n.]
   1. To put forth blossoms or flowers; to bloom; to blow; to
      flower.
      [1913 Webster]

            The moving whisper of huge trees that branched
            And blossomed.                        --Tennyson.
      [1913 Webster]

   2. To flourish and prosper; to develop into a superior type.
      [1913 Webster]

            Israel shall blossom and bud, and full the face of
            the world with fruit.                 --Isa. xxvii.
                                                  6.
      [1913 Webster]

   3. to appear or grow as if by blossoming; to spread out
      rapidly.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

blossoming \blossoming\ n.
   the process of budding and unfolding of blossoms.

   Syn: flowering, inflorescence, anthesis, efflorescence.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

blossoming
    n 1: the time and process of budding and unfolding of blossoms
         [syn: blossoming, flowering, florescence,
         inflorescence, anthesis, efflorescence]