Green’s Dictionary of Slang

a general intensifier.

[c.1610		Shakespeare Winter’s Tale III ii: That did but shew thee, of a foole, inconstant, And damnable ingratefull].
[1621		Massinger & Fletcher The Double Marriage V i: I am damnably hungry].
1806		G. Colman Yngr John Bull II i: The rising generation wants a new dictionary, damnably.
1819		Beppo in London cii: Even C—lm—n [...] Declar’d ‘’twould d—nably annoy the fools!’.
1825		‘The Margate Hoy’ The Universal Songster I 6: Oh, I’m damnably sick!
1827		J.J. Stafford Love’s Frailties II i: What a damnable unfortunate fellow I am!
1838		Lytton Lady of Lyons II i: Now you understand me, My dear, most dear---Oh damnably dear Sir!
1841		D. Boucicault London Assurance in London Assurance and Other Victorian Comedies Act II: I am only in the habit of receiving compliments from the fair sex. Men’s admiration is so damnably insipid.
1854		Waterford Mail 13 May 3/4: Either Dr Gray or Mr Scully must therefore have lied wilfully and ‘most damnably’.
1867		G.W. Harris Sut Lovingood’s Yarns 190: The thing got tu be durn’dably mix’d up.
1871		Dundee Courier 13 Dec. 3/6: he hadbrought a charge against a fellow-constable, and altogether behaved ‘most damnably’.
1884		Gloucester Citizen 18 Nov. 3/5: The last of whom are still taking milk from mother’s chest, and are damnably noiseful.
1897		Orleans Co. Monitor (Barton, VT) 21 June 6/3: The most damnably corrupt thing on earth is American politics.
1909		Yorks. Eve. Post 18 Feb. 6: I am damnably well up in precise writing, drafting [...] and office work.
1915		Birmingham Gaz. 3 July 4/7: Probably the chief secret of Darwin’s happy marriage is that the wife [...] was not ‘damnably clever’ as Mrs Carlyle was.
1921		A.A. Milne Dover Road in Three Plays (1922) Act I: It’s interfering of me, damnably interfering.
1933		E. Arnot Robertson Ordinary Families 259: Damnably unfair, but that doesn’t matter.
1937		News (Frederick, MD) 3 Sept. 11/2: It complicated the situation damnably.
1947		S.J. Perelman Westward Ha! 79: It was most damnably hot.
1954		Aberdeen Eve. Exp. 4 Sept. 5/4: He was still damnably tired.
1968		P. Barnes The Ruling Class I xv: We Gurneys have always been damnably virile.