Are yams and sweet potatoes the same?
1919, 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).
Basketball sense is first recorded 1937 as a verb, 1971 as a noun (earlier dunk shot). German-American Anabaptist sect of Dunkers (who baptize with triple immersion) first recorded by that name 1756.
[fr Pennsylvania German dunken, ''dip'']