The Collaborative International Dictionary of English v.0.48:

Pantheism \Pan"the*ism\, n. [Pan- + theism.]
   The doctrine that the universe, taken or conceived of as a
   whole, is God; the doctrine that there is no God but the
   combined force and natural laws which are manifested in the
   existing universe; cosmotheism. The doctrine denies that God
   is a rational personality.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pantheism
    n 1: (rare) worship that admits or tolerates all gods
    2: the doctrine or belief that God is the universe and its
       phenomena (taken or conceived of as a whole) or the doctrine
       that regards the universe as a manifestation of God

The Devil's Dictionary (1881-1906):

PANTHEISM, n.  The doctrine that everything is God, in
contradistinction to the doctrine that God is everything.