an intense, sometimes
short-lived interest in a subject, which makes it seem like everything you encounter is related to and/or reminds you of that theory, area, object, etc. Also the tendency to gather and
hoarde knowledge,
trivia, etc about your subject.
Lately I've had an infactuation with all things Madagascan, especially
lemurs. I thought I heard a sifaka in the tree at my
bus stop this morning, but it turned out to be the
neighborhood's cat-of-the-week in heat.