It has been said it is dangerous to assert a negative. I still remember "bijou, caillou, chou, genou, hibou, joujou, pou"
all of which form plural by adding "x" which is not pronounced. Obviously the dictionary was referring to "x" where it is pronounced in a few words. It was not a thing I could copy and paste readily. Thank you AnnaS for setting things straight. I love being taken to the woodshed in a worth cause. Bill