Green’s Dictionary of Slang

nudity; esp. in phr. in the altogether, naked.

1890		A.J. Vogan Black Police 193: A certain yellow tone of colour [...] pervades the ‘altogether’ of the old man, for the iron-rust and clay-stains of years of lonely toil [...] have dyed the skin.
1894		G. du Maurier Trilby 17: I’m posing for Durien, the sculptor [...] I pose to him for the altogether.
1897		H. Lawson ‘A Little Mistake’ in Roderick (1967–9) I 318: ’Twas the custom still with the local blacks / To cadge in the ‘altogether’.
1900		Nat. Police Gaz. (NY) 8 Sept. 6/1: [headline] bathed in the altogether / [...] / shocked a newport ’cop’.
1902		Bulletin (Sydney) 18 Oct. 23/2: [A] landlady was discoursing to an elderly maiden lodger on the shifts to which Brown – a lodger then under a cloud – was put, even to the extent of retiring to his lonely couch in the altogether, because his only pair of pyjamas were at the wash.
1914		Truth (Melbourne) 31 Jan. 7/3: [headline] Frolics at Freshwater [...] Tango and Tummy-Rub in the Altogether.
1924		Galsworthy White Monkey 160: Yes bring him to-morrow; but, if I can persuade her, it’ll be in ‘the altogether’.
1932		Nottingham Eve. Post 6 Feb. 5/5: The practice of posing ‘in the altogether’ is quite common, and not looked upon with disfavour.
1942		(con. 1890s) S. O’Casey Pictures in the Hallway 297: Supposed to be Vaynus. Naughty girl in the altogether.
1968		A. Burgess Enderby Outside in Complete Enderby (2002) 266: I suppose you’ll be sleeping in your shirt or in the altogether.
1981		H. Gould Fort Apache, The Bronx 182: Tell me that chick’s name, and I’ll go inside and get you a pair of pants and a coat. Or else you’re gonna ride to the precinct in the altogether.
1999		Guardian G2 3 Dec. 18: He’s wearing his altogether, his birthday suit.
2024		J. Meades Empty Wigs (t/s) 751: As Dad used to say: [he was] stark b*ll*ck naked, all but. He was in his birthday suit! The altogether!