obsession

noun4

1. •
   a feeling that will not go away, making someone think about one thing and forget the rest

   • My obsession with rugby resulted in me spending years following the sport.
2. •
   An idea that engenders a compulsive or irrational preoccupation, or the preoccupation thereby engendered.

   • The downfall of the chairman is an obsession that consumes Laura's time.
3. •
   An activity or entity that inspires a compulsive and potentially unhealthy fixation, or the fixation thereby inspired.

   • Editing Wikipedia started as a hobby, but it's turned into a complete obsession of mine.
   • His current obsession is getting that law passed.
4. •
   Influence or control by evil spirits without possession.

   • They should see that a perception of their identification with the Victor of Calvary is absolutely necessary if they are to constantly and victoriously resist the obsession of evil spirits. — 1999