junkie

noun2

1. •
   (slang, offensive) A narcotics addict, especially a heroin user.

   • Rats in the front room, roaches in the back / Junkies in the alley with a baseball bat — 1982
2. •
   (slang) An enthusiast of something.

   • English people are travel junkies, but Americans hardly ever leave their state.
   • My uncle is a classic-car junkie.