Wiktionary
a. (context informal English) contemptible foolish.
Usage examples of "damnfool".
There were three Russian observers in England last summer going round these damnfool horse trials.
Because of that damnfool letter you and the others wrote to the Times, she described you as arrogant and overpaid.
Don't think for a second that I don't know you're sitting in that cane-bottom chair, grinning at this damnfool machine and forcing me, your own flesh and blood, who suffered through seventeen hours of back labor—.
Like this bit about the freedom of religion not meaning the town can't put up a creche at Christmas, the speech not including fornicating in the streets, assembly not including rioting, property subject to legal usage, and trial not meaning damnfool stuff like throwing anyone who knows anything off a jury, things like that.
He kited back along the wall as the damnfool spacer came in looking for him.
I have responsibilities closer to hometo my employees, to my staff, to the people who depend on me personally to be there, and not go haring off on some kind of damnfool idealistic crusade designed to get someone close to me out of a midterm exam.