n. negative criticism

n. a bad experience; "the school of hard knocks"

n. a vigorous blow; "the sudden knock floored him"; "he took a bash right in his face"; "he got a bang on the head"

v. rap with the knuckles; "knock on the door"

v. 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"

v. make light, repeated taps on a surface; "he was tapping his fingers on the table impatiently"