The Collaborative International Dictionary of English v.0.48:

New Thought \New` Thought"\
   Any form of belief in mental healing, other than (1)
   Christian Science and (2) hypnotism or psychotherapy. It was
   practised in the 19th century, and its central principle was
   affirmative thought, or suggestion, employed with the
   conviction that man produces changes in his health, his
   finances, and his life by the adoption of a favorable mental
   attitude. As a therapeutic doctrine it stands for silent and
   absent mental treatment, and the theory that all diseases are
   mental in origin. As a cult it has its unifying idea the
   inculcation of workable optimism in contrast with the "old
   thought" of sin, evil, predestination, and pessimistic
   resignation. The term is essentially synonymous with the term
   High Thought, used in England. -- New` Thought"er, n. --
   New` Thought"ist, n.
   [Webster 1913 Suppl. +PJC]