From WordNet (r) 2.0 (August 2003) [wn]:
junky
n 1: a narcotics addict [syn: drug addict, junkie]
2: someone who is so ardently devoted to something that it
resembles an addiction; "a golf addict"; "a car nut"; "a
news junkie" [syn: addict, nut, freak, junkie]