Green’s Dictionary of Slang

knocking n.

1. sexual intercourse.

1654		Mercurius Fumigosus 16 13–20 Sept. 146: At first encounter, there had been old knocking, but that the Shee-Troopers yeelded upon quarter, delivering up their Arms, upon promise of their lives, some thrusts were made on both sides.
1730		A. Ramsay Fables and Tales in Poems II (1800) 170: For nought delights him mair than knocking.
1762		Bridges Homer Travestie (1764) II 171: Besides all this, he’ll throw you in / Seven handsome wenches that can spin, / So you may have your fill of knockings, / And never want good yarn for stockings.

2. negative criticism.

1900		Punch 31 Jan. 80/2: ...and the wine-merchants will suffer, and the tobacconists get a bit of a knocking.
1906		Daily Trib. (Bismarck, N.D.) 12 Apr. 2/6: There has come to be a new trade or profession [...] which might be described by the slang word ‘knocking’ and the creed of the ‘knockers’ [is] ‘When you see a horse, hit him on the nose’.
1913		H.G. Van Campen ‘Woes of Two Workers’ in McClure’s Mag. Aug. 192/2: I wisht you’d can some of that knockin’. Spreadin’ the report that maw’s only a bottle blonde, an’ was married an’ Renoed four times before we come East, has made her terrible grieved.
1919		Van Loan ‘Excess Baggage’ in Score by Innings (2004) 398: The anvil chorus was a dying whisper beside the knocking that came off in the next few days.

In compounds

knocking-jacket (n.)

a nightdress.

1699		‘Prodigals Resolution’ in Playford Pills to Purge Melancholy I 60: In Play-houses I’ll spend my days, / For they’re hung round with Plackets; / Ladies make Room, behold I come, / Have at your Knocking Jackets.
1719		in D’Urfey Pills to Purge Melancholy III 48: Ladies, make room, behold I come, Have at your knocking jackets.
1821		‘A Real Paddy’ Real Life in Ireland 51: Sal’s aviary of game made his eyes sparkle with glee; they had just risen, hastily slipped on their knocking-jackets.
1989		H. Rawson Dict. of Invective (1991) 227: The pregnant sense, however, is in keeping with the earlier use of knock to mean copulation and knocker to mean penis; with such derivative expressions as knocking-house, a brothel, and knocking-jacket, a nightgown.