Definition of "obsessive"

obsessive

/əbˈsɛsɪv/

adjective
comparative more obsessive, superlative most obsessive
1. Prone to cause obsession.
2. Having one thought or pursuing one activity to the absolute or nearly absolute exclusion of all others.
3. Excessive, as results from obsession.
  Quotations
  Yes, there were instances of grandstanding and obsessive behaviour, but many were concealed at the time to help protect an aggressively peddled narrative of [Oscar] Pistorius the paragon, the emblem, the trailblazer.
  2014 October 21, Oliver Brown, “Oscar Pistorius jailed for five years – sport afforded no protection against his tragic fallibilities: Bladerunner's punishment for killing Reeva Steenkamp is but a frippery when set against the burden that her bereft parents, June and Barry, must carry ”, in The Daily Telegraph (Sport)‎
noun
plural obsessives
1. A person who is obsessed, who has an obsession.