From WordNet (r) 3.0 (2006) [wn]:
junkie
n 1: a narcotics addict [syn: drug addict, junkie, junky]
2: 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" [syn: addict, nut,
freak, junkie, junky]