Where does “moistour” come from?

moistour (Old French) comes from Old French moisteur, from Old French moiste, from Vulgar Latin mucidus, from Latin mucidus, from Latin mūceō, from Latin mūcus, from Proto-Italic moukos, from Proto-Indo-European mew-k- — slimy, slippery; slip, slime.

moistour (Old French): Alternative form of moisteur; moisture, dampness,...