any member of the spider family Theridiidae (order Araneida). The more than 1,000 species of comb-footed spiders are distributed around the world, and they include the black widow. The webs of theridiids consist of an irregular network of threads from which the spider often hangs. The common name of the group is derived from a row of bristles on the tarsus, or “foot,” of the hind legs, which are used to throw silken strands over prey to ensnare it.