1919, "to dip (something) into a beverage or other liquid," American English, from Pennsylvania German dunke "to dip," from Middle High German dunken, from Old High German dunkon, thunkon "to soak," from PIE root *teng- "to soak" (see tincture). The basketball sense "jump up and push (the ball) down through the basket" is recorded by 1935 as a verb (implied in dunking), 1967 as a noun (earlier dunk shot, 1950). Related: Dunked.
popular name of a German-American Anabaptist sect, 1756, from (Pennsylvania) German Tunker, from tunken, dunken "to dip, soak" (see dunk (v.)). So called because they practice adult baptism by triple immersion. The proper name is Brethren.