n. 1.the sound of knocking (as on a door or in an engine or bearing) 2.negative criticism 3.a vigorous blow 4.a bad experience 5.the act of hitting vigorously knock v. 1.deliver a sharp blow or push :"He knocked the glass clear across the room" 2.rap with the knuckles 3.knock against with force or violence 4.make light, repeated taps on a surface 5.sound like a car engine that is firing too early 6.find fault with
