Green’s Dictionary of Slang

a general intensifier: completely, utterly, absolutely; also used as adj.

1592		Arden of Feversham line 177: I will rid myne elder brother away: And then the farme of Bolton is mine owne. Who would not venture upon house and land, When he may haue it for a righte downe blowe.
1683		W. Kennett (trans.) Erasmus Witt against Wisdom (1509) 97: [R]ight down honest, well-meaning people, such as understood plain sense.
c.1815		J.K. Paulding Bucktails (1847) I i: I’m right down home-sick.
1833		Middleburg Free Press (VT) 22 May 1/1: ‘It’s a right down gentleman’s complaint’.
1837		R.M. Bird Nick of the Woods I 37: A right-down soldier-looking Captain he is too.
1840		T. Haliburton Clockmaker III 174: It’s the real right down thing itself.
1847		‘Epistle from Joe Muggins’s Dog’ in Era (London) 12 Sept. 4/3: It’ll be no child’s play, you’ll see, but a right- down arnest [sic] affair.
1853		T. Haliburton Sam Slick’s Wise Saws I 68: I make myself master of the subject [...] and then go at it in rale right down airnest.
1866		J. Greenwood Little Ragamuffin 140: Unless a chap is bowl’d out in right down reg’ler priggin’, they dursn’t call him a thief.
1876		C. Hindley Life and Adventures of a Cheap Jack 199: Having learned all the patter-clatter, he used to work away in right down earnest.
1884		(con. c.1840) ‘Mark Twain’ Huckleberry Finn 126: We are right down sorry for you, but we—well hang it, we don’t want the small-pox.
1895		Queenslander (Brisbane) 2 Mar. 404/1: With a head-rope I’m a daisy / And a rightdown bobby-dazzler at a pub.
1899		R. Whiteing No. 5 John Street 95: A right-down ‘raughty gal’ leading her alley to battle against the Roman ‘slops’.
1901		Bulletin (Sydney) 20 Jul. 32/2: ‘Everybody says he’s looking right-down ill,’ declared Susan.
1908		Sporting Times 16 May 1/5: It was a real, right-down jolly old English wedding.
1912		E. Pugh Harry The Cockney 191: This house [...] is what I call a regular right-down rotten house.
1929		E. Dahlberg Bottom Dogs 73: He got awfully white looking, and the fellas felt rite down sorry for him.