knocking

1. 1
   noununcountable

   An act of striking a surface to produce a sound, or the sound that results from it.

   Her knocking grew louder when no one came to answer.

   The steady knocking of a woodpecker echoed through the forest.

   Similarrapping, tapping, banging, pounding, hammering

   Note

   As a countable noun it takes the plural freely, and knockings tends to mean a series of raps whose source is unclear rather than one caller at the door. W. B. Yeats, in The Celtic Twilight (1893), hears the spirits who attend the dying in "strange openings and closings and knockings". In the plural the word leans toward the eerie, or toward sound treated as texture.

2. 2
   verb

   Present participle of knock.

   He is knocking loudly, hoping someone will let him in.

   They were knocking at the window to get our attention.

   Note

   One -ing form does two jobs here. It builds the progressive (she was knocking at the window) and also works as a gerund (knocking got no answer). Modern English knocks on or at a door. Using the door as a direct object, as in knocking the door, now sounds dated. The colloquial sense of criticizing keeps its object, though: critics kept knocking the film.

3. 3
   noununcountable

   A repetitive ping or knock from an engine caused by uncontrolled explosions in the combustion chamber.

   Mechanics traced the knocking to poor-quality fuel in the tank.

   Under heavy load, the knocking became impossible to ignore.

   Similarpinking, pinging, detonation

   Note

   Motorists have talked about engine knocking since at least 1914, when The Motor Cycle printed a letter on the subject. The noise is only the symptom. The fault behind it is fuel exploding in uncontrolled bursts in the combustion chamber, and the same sound is also called a ping. It is not always heard: at high speed it can go unnoticed by the driver, so a quiet engine is no guarantee.

Showing meanings only. Show all 3