Knock

1. To strike for admittance; to rap upon, as a door.
2. To strike with something hard or heavy; to move by striking; to drive (a thing) against something; as, to knock a ball with a bat; to knock the head against a post; to knock a lamp off the table.
3. To drive or be driven against something; to strike against something; to clash; as, one heavy body knocks against another.
4. A stroke, as on a door for admittance; a rap.
5. To strike or beat with something hard or heavy; to rap; as, to knock with a club; to knock on the door.
6. A blow; a stroke with something hard or heavy; a jar.