Longman Dictionary of Contemporary English
Douglas Harper's Etymology Dictionary
1837, U.S. slang euphemism for hell-fired.
Wiktionary
a. (context chiefly US informal English) extreme, excessive. adv. (context chiefly US intensifier informal English) extremely, inordinately, very.
WordNet
Usage examples of "all-fired".
And if Miz Charles is so all-fired married, what's she doing here every day, making eyes at that ol' boy on the street?
If my maunderings are as all-fired important to you as you claim, then you'll show up and listen.
If my maunderings are as all-fired important to you as you claim, then you’ll show up and listen.
By the time the roads were passable two days later, Jacob Overby, the rancher, had hinted broadly that there was no need for the Martins to take off in such an all-fired hurry.
This rabbi thinks he's so all-fired important that the treaty signing will be upstaged by the reading of his research paper.