Definition of heroin noun from the Oxford Advanced Learner's Dictionary

 

heroin

 noun
noun
BrE BrE//ˈherəʊɪn//
 
; NAmE NAmE//ˈheroʊɪn//
 
[uncountable] Addiction
 
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a powerful illegal drug made from morphine, that some people take for pleasure and can become addicted to a heroin addict a fatal heroin overdose See related entries: Addiction Word Origin late 19th cent.: from German Heroin, from Latin heros ‘hero’ (because of its effects on the user's self-esteem).
See the Oxford Advanced American Dictionary entry: heroin