Science / Psychiatry / Obsession: Recurrent and persistent thought, impulse, or image experienced as intrusive and distressing. Recognized as being excessive and unreasonable even though it is the product of ones mind. This thought, impulse, or image cannot be expunged by logic or reasoning.
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Obsession Noun Synonyms: fixed idea, id´┐Że fixe, fixation, conviction, preoccupation, prepossession, passion, mania, phobia, hang-up, thing