Well, my Websters has one definition as a noun..."surface gloss"
So, I guess 'nail polish' works in that sense. :) I do use the term nail polish, and because I am consistant, I also say "I am going to polish my nails" But, then, the whole thing is moot for me, because I neither polish my nails nor apply nail polish these days......opting instead to have the solar nails applied by a nail technician....in which case they really are "polished" by their nifty little polishing machine!