obsessive
This term describes a state of preoccupation that transcends mere interest, implying a loss of control or a compulsive drive. It often carries a negative or clinical connotation, suggesting that the focus has become intrusive or detrimental to the individual's well-being. When used as a noun, it refers to the person themselves. While the adjective can describe a passionate hobbyist in a casual sense, the noun form frequently highlights the eccentricity or rigidity of the person's behavior.
Meanings
Thinking about something or someone too much or for too long, often to an unhealthy or extreme degree.
"He has an obsessive interest in the history of the Roman Empire."
Characterized by an obsession, particularly in a clinical or psychological sense involving repetitive and uncontrollable thoughts.
"The patient exhibited obsessive tendencies that interfered with her daily routine."