The genus was named in 1971 by Aleksandr Grigorevich Sharov.[1] The type species is Sordes pilosus. The genus name means "filth" or "scum" in Latin, a reference to evil spirits in local folklore. The specific name is Latin for "hairy"; despite sordes being feminine, it has not yet been emended to pilosa. Sordes had a 0.63 m (2 ft) wingspan. The wings were relatively short. Sordes had, according to Sharov and Unwin, wing membranes attached to the legs and a membrane between the legs. It had a short neck. It had a long tail, accounting for over half its length, with at the end an elongated vane.