knock

the sound of knocking (as on a door or in an engine or bearing)

“the knocking grew louder”

negative criticism

a vigorous blow

“the sudden knock floored him”

“he took a bash right in his face”

“he got a bang on the head”

a bad experience

“the school of hard knocks”

the act of hitting vigorously

“he gave the table a whack”

deliver a sharp blow or push

“He knocked the glass clear across the room”

rap with the knuckles

“knock on the door”

knock against with force or violence

“My car bumped into the tree”

make light, repeated taps on a surface

“he was tapping his fingers on the table impatiently”

sound like a car engine that is firing too early

“the car pinged when I put in low-octane gasoline”

“The car pinked when the ignition was too far retarded”

find fault with; express criticism of; point out real or perceived flaws

“The paper criticized the new movie”

“Don't knock the food — it's free”