Green’s Dictionary of Slang

indescribables n.

trousers.

1794		Sporting Mag. Jan. III 221/2: That hebdomodal display of foppery, frivolity, and fashion, has already begun to sport its vernal variety of indescribables.
1821		Hants Chron. 4 June 2/4: Oh, the eye with pleasure dwells / On his white jean indescribables.
1836–7		Dickens Pickwick Papers (1999) 216: Mr Trotter [...] gave four distinct slaps on the pocket of his mulberry indescribables.
1841		Hereford Times 31 July 2/8: A singular litttle man in olive brown coat and blue indescribables.
1854		W.W. Smyth A Year with the Turks 79: The trowsers [sic] are often of red or chocolate coloured stuffs, and cut in such a manner as to allow of freer motion than the full indescribables of the genuine Turk.
1860		Lloyd’s Wkly Newspaper 9 Sept. 6/2: He was [...] dressed in a black frock coat, black indescribables, and a yellowish vest and white ‘next-to-me’.
1865		Dundee Courier 11 July 3/5: The floating silks, and airy indescribables of the Mexican belles.
1883		Tamworth Herald 3 Feb. 8/5: One of the prisoners appeared [...] with nothing beyond a shirt and that article of men’s attire which is termed his ‘indescribables’.
1889		Sheffield Eve. Teleg. 4 Sept. 2/2: Mr Montmorency was ‘suit-ed’ in an ‘elegant loose-fitting pair of indescribables’.