Real Dictionary

crab
countable noun: A crab is a sea creature with a flat round body covered by a shell, and five pairs of legs with large claws on the front pair. Crabs usually move sideways.

crab in American English 1
any of various decapods with four pairs of legs, one pair of pincers, a flattish shell, and a short, broad abdomen folded under its thorax
noun: any decapod crustacean of the suborder Brachyura, having the eyes on short stalks and a short, broad, more or less flattened body, the abdomen being small and folded under the thorax

crab in American English 2
crab apple
of a crab apple or the tree that it grows on
to complain peevishly; grumble
to irritate; vex
noun: a crab apple fruit or tree

crab in American English 3
intransitive verb: to find fault; complain
noun: an ill-tempered or grouchy person
transitive verb: to find fault with

Crab in British English
noun

crab in British English 1
noun: any chiefly marine decapod crustacean of the genus Cancer and related genera (section Brachyura), having a broad flattened carapace covering the cephalothorax, beneath which is folded the abdomen. The first pair of limbs are modified as pincers

crab in British English 2
noun: an irritable person
verb: to find fault; grumble

crab in British English 3
noun