Green’s Dictionary of Slang

1. an effeminate man, presumably a homosexual; also as adj.; thus Miss Nancyish, effeminate; Miss-Nancyism, effeminacy.

1828		W. Carr Dialect of Craven II 2: A miss-nancy, an effeminate, insignificant man.
1848		Bartlett Dict. Americanisms.
1850		(con. 1843) Melville White-Jacket (1990) 247: There’s that nambypamby Miss Nancy of a white-face, Stribbles, who, the other day [...] ordered me to hand him the spyglass, as if he were a commodore.
1872		‘Mark Twain’ Roughing It 178: [They] did not go jiggering up and down after the silly Miss-Nancy fashion of the riding-schools.
1874		M. Clarke Term of His Natural Life (1897) 272: Now then, Miss nancy [...] what’s the matter with you!
1883		Phila. Times 2 July n.p.: The milksops and Miss-Nancys among the young men, etc [F&H].
1898		Sporting Times 19 Feb. I 3: But do you think we enjoyed these superfine Miss Nancies a quarter as much as we did the daring darlings who subsequently lured them down the Madeira Drive? [F&H].
1901		Sydney Sportsman (Surry Hills, NSW) 25 Sept. 1/3: Young men that are poor must not indulge in any pastime on a Sunday, but the well-to-do Miss Nancys may, and do.
1912		R.W. Brown ‘Word-List From Western Indiana’ in DN III:viii 583: Miss Nancy, n. An effeminate man [...] ‘He’s a regular Miss Nancy’.
1926		Wood & Goddard Dict. Amer. Sl.
1989		H. Rawson Dict. of Invective (1991) 252: Nancy, a rhyme on fancy, and usually reserved for effeminate men or outright catamites, as in Miss Nancy or nancy-boy.
1999		G. Seal Lingo 115: There seems to have been no shortage of terms used either by homosexuals themselves and/or by non-homosexuals, such as miss nancy (surviving in Lingo as nancy or nancy boy).

2. in attrib .use of sense 1.

1848

‘Epistle from Joe Muggins’s Dog’ in Era (London) 4 June 4/1: Sich a kiddy, Miss Nancy swell as the cove looked I never seed afore, and don’t wish to do agin. Poor John Davis, why don’t you take to an honest calling, and not turn bonnet for a tailor?