addict

Noun

• someone who is physiologically dependent on a substance; abrupt deprivation of the substance produces withdrawal symptoms

• someone who is so ardently devoted to something that it resembles an addiction
  • a golf addict
    
  • a car nut
    
  • a bodybuilding freak
    
  • a news junkie
    

Verb

• to cause (someone or oneself) to become dependent (on something, especially a narcotic drug)

Related words

• Synonyms: 
  nut , freak , junkie , junky , hook