- any freshwater decapod crustacean of the genera Astacus and Cambarus, closely related to but smaller than the lobsters.
- any of several similar marine crustaceans, especially the spiny lobster.
- any freshwater decapod crustacean of the genera Astacus and Cambarus, resembling a small lobster
- any of various similar crustaceans, esp the spiny lobster