an order of crustaceans (including true crabs) having a reduced abdomen folded against the ventral surface
source: WordNet 3.0
A group of decapod Crustacea, including the common crabs, characterized by a small and short abdomen, which is bent up beneath the large cephalo-thorax. [Also spelt Brachyoura.] See Crab, and Illustration in Appendix.
