Dope
early 19th century (in the sense ‘thick liquid’): from Dutch doop ‘sauce’, from doopen ‘to dip, mix’.
wiktionary
From Dutch doop(“thick dipping sauce”), from Dutch dopen(“to dip”), from Middle Dutch dopen, from Old Dutch *dōpen, from Frankish *daupijan, from Proto-Germanic *daupijaną.
Sense “narcotic drug” originally from viscous opium pastes, “insider information” perhaps from knowing which horse had been doped in a race. [1] Related to English dip and German taufen.
etymonline
dope (n.)
1807, American English, "sauce, gravy; any thick liquid," from Dutch doop "thick dipping sauce," from doopen "to dip" (see dip (v.)). Used generally by late 19c. for any mixture or preparation of unknown ingredients.
Extension to "narcotic drug" is by 1889, from practice of smoking semi-liquid opium preparation. Meaning "foolish, stupid person" is older than this (1851) and may be from the notion of "thick-headed," later associated with the idea of "stupefied by narcotics."
Sense of "inside information" (1901) may come from knowing before the race which horse had been drugged to influence performance (to dope (v.) in this sense is attested by 1900). Dope-fiend is attested from 1896, "a victim of the opium habit."
dope (v.)
"administer a drug to," 1889, from dope (n.). Related: Doped; doping.
