Meaning of knock in English
I heard two knocks on the door.
    
    
    
            
    a loud knock
    
        
        
    1. hit noisily something such as a door in order to inform one’s arrival
knock on[at] the door
    
    2. (cause to) hit against accidentally
knock one's foot against[on] the table ー stub one's toe into the table
    
      
