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.

[French : folie , madness + à , between + deux , two .]

A condition in which two individuals who share a close relationship experience the same delusions or hallucinations as the result of a mental disorder such as schizophrenia affecting one or both of them. Also called shared psychotic disorder .

(Psychiatry) psychiatry mental illness occurring simultaneously in two intimately related persons who share some of the elements of the illness, such as delusions

folie à deux

This mental disorder, present in two closely associated individuals at once, most commonly occurs in a husband and wife.

Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited