Crud meaning : Dirt, filth or refuse. (by extension) Something of poor quality. A contemptible person. Mixed impurities, especially wear and corrosion products in nuclear reactor coolant. A heavy wet snow on which it is difficult to travel. Feces; excrement. Venereal disease, or (by extension) any disease. A fast-paced game, loosely based on billiards or pool, with many players participating at the same time. Non-vulgar interjection expressing annoyance, anxiety, etc.; sugar, damn.