knock >> /nɑk/
Definition: [verb] Strike a surface noisily to attract attention, especially when waiting to be let in through a door.
Example: I knocked on the kitchen door
Definition: [verb] Collide with (someone or something), giving them a hard blow.
Example: he deliberately ran into her, knocking her shoulder
Definition: [verb] Talk disparagingly about; criticize.
Definition: [noun] A sudden short sound caused by a blow, especially on a door to attract attention or gain entry.
Example: There was a sudden knock at the door, the noise seemingly unnatural and loud in the silence that I had gotten accustomed to in the past half-hour.
Definition: [noun] A blow or collision.
Example: the casing is tough enough to withstand knocks
Definition: [noun] A critical comment.