Describes a film that people under 18 are not allowed to see, because it has sex or violence in it. It came from the old rating systems in Britain and America where a film was given the letter X, and it works as an adjective, usually before a noun: an X-rated film, an X-rated video. In everyday use, though, X-rated has drifted, and this is the part worth knowing. Because the American X rating was quickly taken over by the pornography business — hence XXX on shop signs — most English speakers now hear X-rated as meaning pornographic, not merely adult. Both official systems have moved on (Britain uses 18, America uses NC-17), so the word survives less as a real rating and more as a way of saying "very rude indeed." You will hear it stretched, often half-joking, to all sorts of things that have nothing to do with film: an X-rated joke, an X-rated text message, an X-rated argument the neighbours could hear through the wall. It is casual, spoken English, and slightly dated — a word your teacher's generation reaches for more readily than a teenager would.