The Collaborative International Dictionary of English v.0.48:

Preexistence \Pre`["e]x*ist"ence\, n.
   1. Existence in a former state, or previous to something
      else.
      [1913 Webster]

            Wisdom declares her antiquity and pre["e]xistence to
            all the works of this earth.          --T. Burnet.
      [1913 Webster]

   2. Existence of the soul before its union with the body; -- a
      doctrine held by certain philosophers. --Addison.
      [1913 Webster]

WordNet (r) 3.0 (2006):

preexistence
    n 1: existing in a former state or previous to something else

The Devil's Dictionary (1881-1906):

PRE-EXISTENCE, n.  An unnoted factor in creation.