Green’s Dictionary of Slang

duchess n.2

[? the diary of Sarah, Duchess of Marlborough (1660–1744), who, following the return of her husband, wrote: ‘Today my Lord returned from the wars and pleasured me twice in his top-boots’]

1. a woman who has intercourse while still half-dressed.

[UK]Grose Classical Dict. of the Vulgar Tongue n.p.: Dutchess, a woman enjoyed with her pattens on.
[UK]Lex. Balatronicum.
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue.

2. a man who has intercourse without removing his boots; thus make a duchess, to have intercourse in this spontaneous manner.

[UK]Grose Classical Dict. of the Vulgar Tongue n.p.: A woman enjoyed [...] by a man in boots, is said to be made a dutchess.
[UK]Lex. Balatronicum.
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue.