The Collaborative International Dictionary of English v.0.48:

Brachyura \Brach`y*u"ra\, n. pl. [NL., fr. Gr. brachy`s short +
   o'yra` tail.] (Zool.)
   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.
   [1913 Webster] Brachyural