Intent attention to or exaggerated enthusiasm for a single topic or concept.
extortionate interest or attention to a singular item or subject.
A pathological obsession with someone, thing or concept.
Derangement for the head in regard of one subject just; also, such a concentration of interest upon a particular topic or train of ideas to show mental derangement.
Insanity which there clearly was a far more or less full restriction associated with the perverted emotional action to a particular industry, as a particular delusion, or an impulse to-do some certain thing. One other emotional functions may show some signs of deterioration.
In popular usage, an unreasonable zeal for or curiosity about some one thing; a craze.