n. 1. the family including the crayfish. Syn. -- Astacidae, family Astacidae. [ WordNet 1.5 ]
‖n. [ L. astacus a crab, Gr. &unr_;. ] (Zool.) A genus of crustaceans, containing the crawfish of fresh-water lobster of Europe, and allied species of western North America. See Crawfish. [ 1913 Webster ]