- 1: a persistent disturbing preoccupation with an often unreasonable idea or feeling; broadly : compelling motivation <an obsession with profits>
- 2: something that causes an obsession
In 19th century psychiatry, monomania (from Greek monos, one, and mania, mania) is a single pathological preoccupation in an otherwise sound mind. Emotional monomania is that in which the patient is obsessed with only one emotion or several related to it; intellectual monomania is that which is related to only one kind of delirious idea or ideas. In 1880, monomania was one of the seven recognized categories of mental illness. After the 1950's monomania was no longer used as a technical term in psychology, and does not appear in the Diagnostic and Statistical Manual of Mental Disorders. However, a number of disorders once classified under monomania survive as impulse control disorders or conduct disorders or delusional disorders.
An idée fixe is a preoccupation of mind held so firmly as to resist any attempt to modify it, a fixation. The name originates from the French [French : idée, idea + fixe, fixed]. Although not used technically to denote a particular disorder in psychology, idée fixe is used often in the description of disorders, and is employed widely in literature and everyday English.