The Collaborative International Dictionary of English v.0.48:

Flotation \Flo*ta"tion\, n. [Cf. F. flottation a floating,
   flottaison water line, fr. flotter to float. See Flotilla.]
   1. The act, process, or state of floating.
      [1913 Webster]

   2. The science of floating bodies.
      [1913 Webster]

   3. (Com. & Finance) Act of financing, or floating, a
      commercial venture or an issue of bonds, stock, or the
      like.
      [Webster 1913 Suppl.]

   Center of flotation. (Shipbuilding)
      (a) The center of any given plane of flotation.
      (b) More commonly, the middle of the length of the load
          water line. --Rankine.

   Plane of flotation, or Line of flotation, the plane or
      line in which the horizontal surface of a fluid cuts a
      body floating in it. See Bearing, n., 9
      (c) .

   Surface of flotation (Shipbuilding), the imaginary surface
      which all the planes of flotation touch when a vessel
      rolls or pitches; the envelope of all such planes.
      [1913 Webster]

WordNet (r) 3.0 (2006):

flotation
    n 1: the phenomenon of floating (remaining on the surface of a
         liquid without sinking) [syn: flotation, floatation]
    2: financing a commercial enterprise by bond or stock shares
       [syn: flotation, floatation]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "flotation":
   coming out, curtain raiser, debut, embarkation, embarkment,
   first appearance, floating, inaugural address, inauguration,
   induction, initiation, installation, installment, introduction,
   issuance, issue, launching, maiden speech, opener, preliminary,
   stock issue, unveiling