Green’s Dictionary of Slang

1. (also dreadnaught) an overcoat; also attrib.

1825		Pierce Egan’s Life in London 18 Dec. 375/2: Bill Stewart; a short, stout, weather-beaten, old man-of-war's man, dressed in a dread nought spencer,.
1836		Yorks. Gaz. 10 Dec. 2/7: The utmost that the council seem likely to dare in the matter of clothing the police, is the replacing the battered old great coats with new and warm dreadnaughts.
1837		R. Barham ‘The Bagman’s Dog’ in Ingoldsby Legends (1840) 327: He’d a ‘dreadnought coat’ and heavy sabots.
1851		Melville Moby Dick (1907) 25: Going to his heavy grego, or wrapall, or dreadnought, which he had previously hung on a chair, he fumbled in the pockets.
1863		N. London News 17 Nov. n.p.: [advert] Richards and Co’s Dreadnaught Overcoats, 21s.
1871		Freeman’s Jrnl 20 Sept. 3/3: Your besd covering will be scanty, but you make up for this [...] by your rug, or your dread-naught (coat).
1874		H. Mayhew London Characters 353: Rough pilot coats, and shiny tarpaulin ‘dreadnaughts’.

2. a male pessary or suppository.

1937–84

Partridge DSUE (1984) 340/2: from 1908.

3. a high, stiff corset.

1937–84

Partridge DSUE (1984) 340/2: from ca. 1909; ob.

4. (Aus. milit.) a prophylactic kit.

1924

(con. WWI) A.G. Pretty Gloss. of Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: dreadnought. V.D. Prophylactic outfit issued to troops before departing on leave.