A narcotics addict
Synonyms:
  1. junkie
  2. addict
  3. burnout
  4. dopehead
  5. doper
  6. drug abuser
  7. drug fiend
  8. drug user
  9. druggie
  10. freak
  11. hophead
  12. narcotics addict
  13. space-cadet
  14. user
  15. junky