Entry 2 senses · 2 variants Webster, 1913 Monomaniac · Mon·oma·ni·ac · IPA /ˌmɑnoʊˈmeɪnɪæk/ n. a. 01 n. A person affected by monomania. 1. A person affected by monomania. 02 a. Affected with monomania, or partial derangement of intellect; caused by, or resulting from, monomania; as, a monomaniacal delusion. 1. Affected with monomania, or partial derangement of intellect; caused by, or resulting from, monomania; as, a monomaniacal delusion.