As a noun:
* The duck waddled across the pond, looking for food.
* He served us a delicious plate of duck à l'orange.
* I love to watch ducks swimming in the park.
* The little girl was terrified of the ducks in the petting zoo.
As a verb:
* He quickly ducked behind the car to avoid being seen.
* The boxer ducked to avoid the punch.
* We ducked our heads as we walked under the low-hanging branches.
* She ducked into the shop to escape the rain.
As an idiom:
* "Don't tell your boss you're quitting, just duck and cover!"
* "He tried to duck responsibility for the mistake."
The meaning of "duck" will depend on the context of the sentence.