"to mend" c.1600, perhaps from Middle French darner "mend," from darne "piece," from Breton darn "piece, fragment, part." Alternative etymology is from obsolete dern (see dern). Related: Darned; darning.
tame curse word, 1781, American English euphemism for damn, said to have originated in New England when swearing was a punishable offense; if so, its spread was probably influenced by 'tarnal, short for Eternal, as in By the Eternal (God), favorite exclamation of Andrew Jackson, among others. Related: darned (past participle adjective, 1806); darndest (superlative, 1844).
(also darned or darnfoolor derned or durned) Wretched; nasty; silly: sentimental songs, darnfool ditties, revival hymns
: She was darn excited
(also darn it or dern it or durn it) An exclamation of disappointment, irritation, frustration, etc: Darn, I've dropped my glockenspiel!
[1780s+; euphemism for damn, which is regarded by some as taboo; probably based on earlier darnation, ''damnation,'' attested by 1798]