Dictionary.com
definitions

mentalism

[men-tl-iz-uh m]
noun
  1. the doctrine that objects of knowledge have no existence except in the mind of the perceiver.
  2. the doctrine that human conduct reflects the operation of a nonmaterial principle.
  3. any psychological theory that accepts as a proper subject of study the mental basis for human behavior.
Compare behaviorism.

Origin of mentalism

First recorded in 1870–75; mental1 + -ism
Related formsmen·tal·is·tic, adjectivemen·tal·is·ti·cal·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for mentalism

mentalism

noun
  1. philosophy the doctrine that mind is the fundamental reality and that objects of knowledge exist only as aspects of the subject's consciousnessCompare physicalism, idealism (def. 3) See also monism (def. 1), materialism (def. 2)
Derived Formsmentalist, nounmentalistic, adjectivementalistically, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012