knocking
n. uncountable A2 Elementary US //ˈnɑkɪŋ// UK //nˈɒkɪŋ// knock·ing
n. the sound of someone hitting a door or a hard surface with their hand. You usually hear this when a visitor wants to come inside.
n. the sound produced by a series of sharp blows against a hard surface, particularly a door. Often used to signal a presence or request entry.
I heard a loud knocking at the front door.
The sudden knocking on the window startled everyone in the living room during the storm.
A persistent knocking from the engine suggested that the vehicle required immediate mechanical attention before the long journey began.
Usage
Often used with the preposition 'at' or 'on' to indicate the location of the sound.