Knock (verb)

1. To strike a surface with a sharp sound.
2. To make a loud noise by striking something.
3. To criticize or express disbelief about something or someone.

Origin:

Middle english: of imitative origin.

Examples:

1. He knocked on the door.
2. The wind knocked over the trash cans.
3. I knocked on the table to get everyone's attention.
4. She knocked on the window to get his attention.
5. He knocked his opponent's performance during the debate.