Nouns become adjectives when the things they describe look like the objects they represent. An afro can look bushy but that doesn't mean it's green and looks like a plant. I think y'all taking it way too serious. I've said my hair felt like steel-wool when I used a product that left it dry and rough. If I later said it was steel-woolly, then that'd be a perfect description of how my hair felt: hard and rough almost like it could scrub rust off iron. Might be an exaggeration coz it wasn't as hard as steel, but words are supposed to give us an understanding of what people are talking about, paint a picture that we can almost touch when we aren't close in person to feel things for ourselves. If the word nappy didn't exist (and I'm so glad it has evolved over time to mean "kinky" coz I think it perfectly describes 4B), then we would have to say "an afro looked bushy" or uncombed 4B hair
like this "looks like beads (beady)". Folks get all up in arms about words because they take innocent words and turn them into insults instead of just looking at the neutral meaning of the word and moving on.
I love that language is so expansive. I love that someone can tell me they're going to change a nappy, and I don't sit there wondering, "you mean downy? or do you mean you're going to work in a textile factory? or do you mean you are going to relax hair and change it from kinky?" I can look at the context in which the word is used and guess they are talking about a diaper. I love that words are so rich in meaning, and think we do ourselves a disservice if we limit their meaning to just that one single one that some smart alec told us years back, and disregard all the other things that have grown from that root of the word that make language so beautiful and rich.