a member of the Church of the Brethren, a denomination of Christians founded in Germany in 1708 and later reorganized in the U.S., characterized by the practice of trine immersion, the celebration of a love feast accompanying the Lord's Supper, and opposition to the taking of oaths and to military service.
1919, from Pa. Dutch dunke "to dip," from M.H.G. dunken, from O.H.G. dunkon, thunkon "to soak," from PIE base *teng- "to soak" (see tincture). Basketball sense is first recorded 1937. German-American Anabaptist sect of Dunkers (who baptize with triple immersion) first recorded by that name 1756.
A basketball field goal scored by putting the ball into the hoop from just beside or above it: Almost all of the baskets were dunks/ basketball courts where the dunks have been so fierce lately(1937+ Basketball)
To dip something into a liquid, esp to dip food into a drink: Scientific temperature readings cannot be taken just by dunking a thermometer on a string(1919+)
To go into the water: Be right back, just want to dunk(1940s+)