definition of Idiosyncracy by The Free Dictionary



n. pl. id·i·o·syn·cra·sies

1. A structural or behavioral characteristic peculiar to an individual or group.

2. A physiological or temperamental peculiarity.

3. An unusual individual reaction to food or a drug.

[Greek idiosunkrāsiā : idio-, idio- + sunkrāsis, mixture, temperament (sun-, syn- + krāsis, a mixing; see kerə- in Indo-European roots).]

id′i·o·syn·crat′ic (-sĭn-krăt′ĭk) adj.

id′i·o·syn·crat′i·cal·ly adv.

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.



n, pl -sies

1. a tendency, type of behaviour, mannerism, etc, of a specific person; quirk

2. the composite physical or psychological make-up of a specific person

3. (Pathology) an abnormal reaction of an individual to specific foods, drugs, or other agents

[C17: from Greek idiosunkrasia, from idio- + sunkrasis mixture, temperament, from sun- syn- + kerannunai to mingle]

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˌɪd i əˈsɪŋ krə si, -ˈsɪn-)

n., pl. -sies.

1. a characteristic, habit, mannerism, etc., that is peculiar to or distinctive of an individual.

2. the physical or mental constitution peculiar to an individual.

3. a peculiarity of the physical or mental constitution, esp. a sensitivity to drugs, food, etc.

[1595–1605; idiosynkrāsía=idio- idio- + syn- syn- + krâsis a blending + -ia -y3]

id`i•o•syn•crat′ic (-oʊ sɪnˈkræt ɪk, -sɪŋ-) adj.

id`i•o•syn•crat′i•cal•ly, adv.

Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


a mannerism, action, or form of behavior peculiar to one person or group. — idiosyncratic, idiosyncratical, adj.

See also: Behavior

-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.

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