Englishbarmy
adjective
British, informal
I think that's a barmy idea:
foolish, stupid, silly, idiotic, half-witted, witless, brainless, mindless, thoughtless, imprudent, incautious, irresponsible, injudicious, indiscreet, unwise, unintelligent, unreasonable;
ill-advised, ill-considered, impolitic, rash, reckless, foolhardy, lunatic;
absurd, senseless, pointless, nonsensical, inane, fatuous, ridiculous, laughable, risible, derisible;
informal dumb, dim, dim-witted, dopey, damfool, half-baked, hare-brained, crackbrained, pea-brained, wooden-headed, thickheaded, nutty, mad, crazy, dippy, cuckoo, screwy, wacky;
British, informal daft, dotty, batty, gormless;
Scottish, & Northern English, informal glaikit;
North American, informal dumb-ass, chowderheaded;
West Indian, informal dotish.
barmy Oxford Dictionary of English