
1) Obsessive thought
Found on
https://www.crosswordclues.com/clue/fixed-idea

An exaggerated notion, belief, or delusion that persists, despite evidence to the contrary, and controls the mind, the obstinate conviction of a psychotic person regarding the correctness of his delusion. ... Synonym: idee fixe, overvalued idea, permanent dominant idea. ... (05 Mar 2000) ...
Found on
http://www.encyclo.co.uk/local/20973

a persistent morbid impression or belief that cannot be changed by reason.
Found on
http://www.encyclo.co.uk/local/21001

Type: Term Definitions: 1. an exaggerated notion, belief, or delusion that persists, despite evidence to the contrary, and controls the mind; 2. the obstinate conviction of a psychotic person regarding the correctness of a delusion. Synonyms: idée fixe, overvalued idea
Found on
http://www.medilexicon.com/medicaldictionary.php?t=43357

a persistent or obsessing idea, often delusional, that can, in extreme form, be a symptom of psychosis.
Found on
https://www.infoplease.com/dictionary/fixed-idea
No exact match found.