Crasseux(-euse) (adj): grimy.
So my 17-yr-old host sister Anna and I are reading an article from the New York Times to practice our English/French, and Anna asks me what the word “grimy” means. Of course I decide to do this English lesson sans dictionnaire because I think that I am the master of all things French, and I say “Oh, grimy, ça veut dire grumeaux.” I go on to use les doigts (fingers) grumeaux as an example. Turns out grumeaux means lumps (plein de grumeaux means lumpy), so really I used lumpy fingers as an example, and crasseux means grimy, which is confusing to an American speaker because don’t grumeaux and grimy sound like presque the same mot?! And where does crasseux come from??
“Like during the winter, your pool gets all lumpy!” I said (in French). “Or if you’re at the beach, your hands and feet get all lumpy by the end of the day” (again, in French). No, your tomato sauce is grumeaux, but your pool and hands are crasseuses…I hope.