simple past tense and past participle of darn
expletives used informally as intensifiers
"he's a blasted idiot"
"it's a blamed shame"
"a blame cold winter"
"not a blessed dime"
"I'll be damned (or blessed or darned or goddamned) if I'll do any such thing"
"he's a damn (or goddam or goddamned) fool"
"a deuced idiot"
"an infernal nuisance"
A minced oath for damned, used to express contempt, exasperation, consternation, etc. towards someone or something.
Damned, extremely.