to drive or be driven against something; to strike against something; to clash; as, one heavy body knocks against another.-to strike or beat with something hard or heavy; to rap; as, to knock with a club; to knock on the door.-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.-to strike for admittance; to rap upon, as a door.-a blow; a stroke with something hard or heavy; a jar.-a stroke, as on a door for admittance; a rap.