A person who uses drugs or doping agents, especially in sports; someone who administers doping substances; or someone who provides information.
Dope + -er (agent noun). The term evolved from dope as slang for inside information, then for drugs, then for performance-enhancing substances in sports.
In sports, 'doper' has become infamous—the massive doping scandals in cycling and athletics revealed how sophisticated athletes and coaches became at evading detection, making it a sports vocabulary that carries real weight.
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