psy·cho·sis (s?-k??s?s)n. pl. psy·cho·ses (-s?z) An acute or chronic mental state marked by loss of contact with reality, disorganized speech and behavior, and often hallucinations or delusions, seen in certain mental illnesses, such as schizophrenia, and other medical disorders.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.psychosis (sa??k??s?s) n, pl -choses (-?k??si?z) (Psychiatry) any form of severe mental disorder in which the individual’s contact with reality becomes highly distorted. Compare neurosis[C19: New Latin, from psycho- + -osis]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014psy?cho?sis (sa??ko? s?s) n., pl. -ses (-s?z). 1. a mental disorder characterized by symptoms, as delusions or hallucinations, that indicate impaired contact with reality. 2. any severe form of mental disorder, as schizophrenia or paranoia. [1840?50] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.psy·cho·sis (s?-k??s?s) Plural psychoses (s?-k??s?z) A mental illness so severe that a person loses the ability to think logically, to communicate, and to relate to others. A person with a psychosis loses contact with reality and often shows dramatic changes in behavior. Psychoses can be caused by diseases affecting the brain.psychotic (s?-k?t??k) adjectiveThe American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.psychosisany severe mental disorder or disease. ? psychotic, n., adj.See also: Insanity-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.