A cowlick is a small bunch of hair on a person's head that grows in a different way from the rest of the hair.
Cowlicks are usually seen as cute or funny, and they can be hard to make look neat.
Examples:
He has a cowlick on the top of his head.
Her cowlick sticks up straight.
The cowlick makes his hair look messy.
The cowlick looks like a little tornado on his head!
Her cowlick is so strong, it can lift things!
The cowlick is like a little mountain in his hair.