Dictionary entry

Monomania

Webster's Dictionary 1913

Mon′o‐ma″ni‐a (?), n. [Mono- + mania.] Derangement of the mind in regard of a single subject only; also, such a concentration of interest upon one particular subject or train of ideas to show mental derangement.

Syn. — Insanity; madness; alienation; aberration; derangement; mania. See Insanity.