Green’s Dictionary of Slang

a synon./euph. for devilishly, damnably.

1833		M. Scott Tom Cringle’s Log (1862) 403: Not so weak as deucedly sore.
1840		Comic Almanack Mar. 220: I was so deucedly ashamed as not to be able to laugh just then.
1850		Thackeray Pendennis II 222: It’s been doosedly dipped and cut into, sir, by the confounded extravygance of your master, with his helbow shakin’, and his bill discountin’.
1850		Thackeray Rebecca and Rowena in Burlesques (1903) 119: Your worship rode so deucedly quick, there was no keeping up with your worship.
1868		H.L. Williams Steel Safe 26: Mr. Newlife is deucedly sharp.
1879		G.R. Sims Dagonet Ballads 102: They’ve got such grand notions of honour, and yet they’re so deucedly mean.
1883		J. Payn Thicker than Water II 137: You would have found it deucedly inconvenient, Ralph, if it had happened to you.
1912		Conan Doyle Lost World 236: ‘It was horrible – but it was doocedly interestin’ too’.
1916		Joyce Portrait of the Artist as a Young Man 85: And deucedly pretty she is too.
1925		Wodehouse Carry on, Jeeves 74: Ocean liners fetch up at the dock at a deucedly ungodly hour.
1928		(con. WWI) H.F. Cruikshank ‘So This Is Flanders!’ Battle Stories July 🌐 I’m afraid I’m deucedly crocked up, ol’ man.