monomania
Concise Oxford English Dictionary © 2008 Oxford University Press:
monomania/mɒnəˈmeɪniə/
▶noun obsessive preoccupation with one thing.
– derivatives
monomaniac noun & adjective,
monomaniacal adjective.
monomaniac noun & adjective,
monomaniacal adjective.
'monomania' also found in these Oxford entries:

