The sound a duck makes.
quack
What a train rides on.
track
The opposite of front.
back
A bag.
sack
A tall pile of stuff.
stack
A little meal.
snack
A group of wild animals that live together.
pack
A small house or cabin.
shack
To be without, or missing something.
lack
Who went up the hill with Jill?
Jack
What colour you mix to get a shade.
black