Green’s Dictionary of Slang

1. a general intensifier, e.g. a proper idiot.

c.1386		Chaucer Reeve’s Tale (1979) line 118: In cradle it lay and was a propre page.
c.1386		Chaucer Cook’s Tale (1979) line 511: A prentis whilom dwelled in oure citee [...] Broun as a berye, a propre short felawe.
1639		Ford Lady’s Trial V i: A proper joining!
1675		Wycherley Country-Wife IV ii: For he’s a proper, goodly strong man.
1824		W. Scott St Ronan’s Well (1833) 331: A proper fellow, sir—one of those fine gentlemen whom we pay for polishing the pavement Bond Street.
1836		T. Haliburton Clockmaker I xi: He was a most an almighty villain, and cheated a proper raft of folks.
1853		T. Haliburton Sam Slick’s Wise Saws II 178: Warnt that a proper lark?
1864, 1867, 1870		Hotten Sl. Dict.
1884		‘’Arry at a Political Pic-Nic’ Punch 11 Oct. 180/1: We got back jest in time for the fireworks, a proper flare-up and no kid.
1902		Bulletin (Sydney) 29 Nov. 31/2: I looked a proper fool, I can tell you, with dust all over me new black suit, standin’ there waitin’ for the bloomin’ tram to get off me hat.
1914		‘Bartimeus’ ‘A Galley’s Day’ Naval Occasions 23: Casey gave a sigh of contentment and handed back an empty glass through the pantry door. ‘Well, sir,’ he said, ‘I reckon that was a proper caper!’.
1922		T.S. Eliot Waste Land 19: The chemist said it would be all right, but I’ve never been the same. / You are a proper fool, I said.
1938		J. Curtis They Drive by Night 164: Sauce she called it, proper sauce.
1943		in T. Harrisson Mass-Observation War Factory: Report 8: I didn’t like that woman at the piano. She looked stuck up and superior. A proper snob she looked.
1959		M. Pugh Chancer 91: He was as two-faced as a cod, a proper chancer.
1969		R. Rendell Best Man To Die (1981) 74: She was a madam, all right, a proper little madam.
1974		D. Ireland Burn 35: Made me look a proper idiot.
1989		Viz June/July 41: The poor bloke must have felt a proper fool.
1998		N. Palmer ‘Vegan Reich’ in Home Suspect Device 11: Dog and his mates were making a proper nuisance of themselves.

2. correct, first-rate, satisfactory, often used ironically.

1837		R.M. Bird Nick of the Woods I 68: A proper fellow as ever you see!
1843		L.H. Medina Nick of the Woods I i: As proper a fellow as ever you saw.
1873		Sl. Dict. 261: A ‘proper man’ generally means a perfect man, as far as can be known.
1878		‘’Arry on the Turf’ Punch 29 Nov. 297/1: I tell yer, old man, it was proper (exceptin’ for my mucker, of course).
1881		Dundee Courier (Scot.) 1 Feb. 7/4: I know her; she’s a proper sort when she has any coin.
1885		Bulletin (Sydney) 4 July 9/1: Why any person of the proper sex – unless one born stone blind, deaf, tongue-tied, bald, and with pronounced spinal curvature – should desire to break off an engagement with Miss Labertouche it is difficult to say.
1902		E. Fisher ‘Sick Cab Rider‘ in Bulletin Reciter n.p.: I don’t think my pyjamas are at the proper thing .
1906		A.H. Lewis Confessions of a Detective 220: Shaving off your mustache was a proper move.
1918		Dagger (London) Dec. I 16/1: Oh ’e was a proper cove was Ginger!
1928		M.C. Sharpe Chicago May (1929) 256: Along the street comes the proper gent.
1938		J. Curtis They Drive by Night 20: Proper game it was. Each knew what the other was after.
1956		J. Curtis Look Long Upon a Monkey 188: If that’s the way you want it, it’s proper by me.
1987		LL Cool J ‘Kanday’ 🎵 I’m in love with the pizznoot, it’s proper as hell.
1991		Eble Campus Sl. Mar.
1997–2000		Da Bomb 🌐 22: Proper: Satisfactory; good.
2007		Twista ‘Whip Game’ 🎵 You know my whip game proper.
2011		Elzhi ‘Detroit State of Mind’ 🎵 For proper scrill or the guap, there’s bills on top of bills.
2018-20		T. Thorne (ed.) ‘Drill Slang Glossary’ at Forensic Linguistic Databank 🌐 Proper - excellent, admirable.