1. [noun] An abrupt rapping sound, as from an impact of a hard object against wood
2. [noun] An impact.
3. [noun] (figurative) criticism
4. [noun] (cricket) a batsman's innings.
5. [noun] (automotive) Preignition, a type of abnormal combustion occurring in spark ignition engines caused by self-ignition or the characteristic knocking sound associated with it.
6. [verb] (intransitive) To rap one's knuckles against something, especially wood.
7. [verb] (transitive) (dated) To strike for admittance; to rap upon, as a door.
8. [verb] (ambitransitive) (dated) To bump or impact.
9. [verb] (colloquial) To denigrate, undervalue.
10. [verb] (soccer) To pass, kick a ball towards another player.
11. [verb] (slang) (dated) (UK) To impress strongly or forcibly; to astonish; to move to admiration or applause.
12. [noun] The sound of knocking (as on a door or in an engine or bearing); 'the knocking grew louder'.
13. [noun] Negative criticism.
14. [noun] A vigorous blow; 'the sudden knock floored him'; 'he took a bash right in his face'; 'he got a bang on the head'.
15. [noun] A bad experience; 'the school of hard knocks'.
16. [noun] The act of hitting vigorously; 'he gave the table a whack'.
17. [verb] Deliver a sharp blow or push :'He knocked the glass clear across the room'.
18. [verb] Rap with the knuckles; 'knock on the door'.
19. [verb] Knock against with force or violence; 'My car bumped into the tree'.
20. [verb] Make light, repeated taps on a surface; 'he was tapping his fingers on the table impatiently'.
21. [verb] Sound like a car engine that is firing too early; 'the car pinged when I put in low-octane gasoline'; 'The car pinked when the ignition was too far retarded'.
22. [verb] Find fault with; express criticism of; point out real or perceived flaws; 'The paper criticized the new movie'; 'Don't knock the food--it's free'.
