Junkie

noun
  1. A person who is addicted to a narcotic drug, especially one who habitually uses illegal drugs. noun
    The alley was a known hangout for junkies looking for their next fix.
    He was once a junkie, but he has been clean for several years now.
  2. A person with an obsessive dependency on something, often used metaphorically for someone who is very enthusiastic or passionate about a particular activity or interest. noun
    She's a real fitness junkie, spending hours at the gym every day.
    As a tech junkie, he always has the latest gadgets and software.