monomania \mon-uh-MAY-nee-uh; -nyuh\, noun
Definition:
1. Pathological obsession with a single subject or idea.
2. Excessive concentration of interest upon one particular subject or idea.
Example:
Fred has an obsession with rubber ducks. It is all he can ever think about. It is a monomania that approaches a frenzy in which girlfriends or wife, family and sleep, mean nothing.
Origin:
Monomania is derived from the Greek elements mono-, "one, single, alone" + mania, "madness, frenzy, enthusiasm."
