glissante. Use Google Translate!
Slippery is glissant(e).
Glissant Pete
slippery is glissant, glissante in French.
French is "français" (feminine: française; plurals: français/ françaises). Here the word français is an adjective, so use a lower-case f. A Frenchman is 'un français', a Frenchwoman is 'une...
Napoleon III