Dictionary.com:
dunk
–verb (used with object) 1. to dip (a doughnut, cake, etc.) into coffee, milk, or the like, before eating.
2. to submerge in a liquid: She dunked the curtains in the dye.
3. Basketball. to attempt to thrust (a ball) through the basket using a dunk shot.
–verb (used without object) 4. to dip or submerge something, oneself, etc., in a liquid: She thinks it's vulgar to dunk. Let's dunk in the pool before dinner.
5. Basketball. to execute or attempt a dunk shot.
–noun 6. any flavorful sauce, dip, gravy, etc., into which portions of food are dipped before eating.
7. Basketball. dunk shot.
http://dictionary.reference.com/search?q=dunk
dunk shot
–noun Basketball. a shot in which a player near the basket jumps with the ball and attempts to thrust it through the basket with one hand or both hands held above the rim.
http://dictionary.reference.com/search?q=dunk%20shot
Here's another one
Merriam-Websters Dictionary:
Dunk
transitive verb
1 : to dip (as a piece of bread) into a beverage while eating
2 : to dip or submerge temporarily in liquid
3 : to throw (a basketball) into the basket from above the rim
intransitive verb
1 : to submerge oneself in water
2 : to make a dunk shot in basketball
http://www.merriam-webster.com/dictionary/dunk
Dunk Shot
: a shot in basketball made by jumping high into the air and throwing the ball down through the basket
http://www.merriam-webster.com/dictionary/dunk+shot
It most definitly qualifies as a dunk.