"sluggish, stupefied," with or as with a narcotic drug; also "stupid" generally, 1896, from dope (n.) + -y (2). Related: Dopiness.
a dopey kid
a dopey answer
door-yard
doo-wop
doozy
dopamine
dope
dopey
doppelganger
Doppler
Dora
dorado
do-rag