knocking

1. gerundparticiplepresentpresent participle and gerund of knock

plural knockings

1. An act in which something is knocked on, or the sound thus produced

   There was no response to continued knockings.

   1901, Carson Jay Lee, Oswald Langdon

   2 more examples

   These strange openings and closings and knockings were warnings and reminders from the spirits who attend the dying.

   1893, W. B. Yeats, The Celtic Twilight

   Recorded live to CD with new instrumentation--artillery shells, tuned suspension cables, boxes filled with springs--and deemphasized guitar parts, it's a beautiful collection of echoes and whispers, drones and knockings, with a gently swelling sense of the sinister.

   2006 July 21, Keith Harris, Monica Kendrick, Peter Margasak, Bob Mehr, Miles Raymer, Neil Tesser, “The Treatment”, in Chicago Reader

2. automotiveA repetitive ping, knock, or similar sound coming from an engine in which there are repeated uncontrolled explosions in the combustion chamber.

   Knocking can also occur at high speed, but that may go undetected by the driver.

   2021 December 28, The Road Ahead, Brisbane, page 56, column 1

   1 more example

   Sir―I was greatly interested in a short article in The Motor Cycle on the subject of engine knocking.

   1914 November 14, The Motor Cycle, London, page 528, column 1