an·ti·psy·chot·ic (?n?t?-s?-k?t??k, ?n?t?-)adj. Counteracting or diminishing the symptoms of psychotic disorders, such as schizophrenia.n. An antipsychotic drug.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.antipsychotic (?ænt?sa??k?t?k) adj (Psychiatry) preventing or treating psychosisn (Pharmacology) any antipsychotic drug, such as chlorpromazine: used to treat such conditions as schizophreniaCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014an?ti?psy?chot?ic (?æn ti sa??k?t ?k, ?æn ta?-) adj. 1. of or pertaining to any of various drugs used in the treatment of psychosis, esp. schizophrenia, and severe states of mania, depression, or paranoia. n. 2. Also called neuroleptic. an antipsychotic drug. [1950?55] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.