Misnomer

I was just thinking of when I was a child and at some point I had heard a term used in conversation, and more through logical deduction than through context clues(I obviously did not understand the adult conversation going on at the time), I figured out what I thought it meant. As a result, when I was at a restaurant and needed a wet-nap to clean my hands, I asked my mom if they had any sanitary napkins. I was quickly corrected, but to this day, I think wet-naps and sanitary napkins were misnamed.