What is the meaning of Doper?

One who uses performance enhancing substances for competitive gain, especially illegally.

One who frequently uses recreational drugs; a druggie; a stoner.

A person employed to apply dope solution during aircraft manufacture.

comparative form of dope: more dope

second-person singular imperative of doprat

baptiser, one who baptises

Anabaptist .mw-parser-output .defdate{font-size:smaller}

to dope; to do doping

to boost (one's performance by doping)

Source: Wiktionary