French word foireux comes from French foire, French -eux (-ous, -y.)

Detailed word origin of foireux

Dictionary entry	Language	Definition
foire	French (fra)	(figuratively, slang) fuckup, mess. (vulgar) diarrhoea A fair, an exposition. A marketplace selling artisan goods.
-eux	French (fra)	-ous, -y.
foireux	French (fra)	(slang) crappy. (slang) ineffective, half-baked.

Words with the same origin as foireux