Merriam-Webster's Collegiate® Dictionary, 11th Edition
DUNK
I. verb see: tinge
Date: 1919
transitive verb to dip (as a piece of bread) into a beverage while eating, to dip or submerge temporarily in liquid, to throw (a basketball) into the basket from above the rim, intransitive verb to submerge oneself in water, to make a dunk shot in basketball,
II. noun
Date: circa 1944
the act or action of dunking