The word "dunk" has multiple meanings depending on its context.
1) In a general sense, it can refer to dipping something into liquid or placing an object in a container filled with liquid and then removing it. For example, you might say that you are going to dunk your cookie into the milk.
2) It can also mean to throw someone into water over their head as a form of playful punishment or celebration. This is often referred to as "dunking" someone.
3) In basketball, it means to score by throwing the ball through the hoop while jumping and then quickly pulling back your arm so that you are holding the ball above your head after you have completed the shot. This move is called a slam dunk because of the forceful motion involved in getting the ball into the basket.
4) Finally, "dunk" can also refer to a type of donut or other sweet baked good made from yeast raised dough that has been cut into holes and then submerged in batter before being fried until golden brown. These are often referred to as "doughnuts," but the term "dunk" is sometimes used interchangeably with this word.