n. A person who is obsessed with a single thing, to the exclusion of other concerns.
adj. Focussed on one thing above all others.
the GNU version of the Collaborative International Dictionary of English
n. A person affected by monomania.
adj. Affected with monomania, or partial derangement of intellect; caused by, or resulting from, monomania.
The Century Dictionary and Cyclopedia
Same as monomaniacal.
n. A person affected by monomania.
n. In law, one who is insane upon some one or more subjects, and apparently sane upon all others.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a person suffering from monomania
Word Usage
"Nothing could be more just than to class him as a monomaniac, for he was one, if by the word monomaniac we designate every man who is dominated by a fixed idea."