<p><strong>Adjective</strong></p><ul><li>being, pertaining to, or resembling an obsession: an obsessive fear of illness</li><li>causing an obsession</li><li>excessive, especially extremely so</li></ul><p><strong>Noun</strong></p><ul><li>someone who has an obsession or obsessions; a person who thinks or behaves in an obsessive manner</li></ul>