Oxford Essential Dictionary
crab
noun
an animal that lives in and near the sea. It has a hard shell and ten legs.
Longman Dictionary of Contemporary English
crab
crab /kræb/ BrE AmE noun
[Sense 1-3: Language: Old English; Origin: crabba]
[Sense 4: Date: 1800-1900; Origin: crabbed]
1. [countable] a sea animal with a hard shell, five legs on each side, and two large ↑claws ⇨ crustacean
2. [uncountable] the flesh of this animal that you can cook and eat:
crab meat
dressed crab (=prepared for eating)
3. crabs [plural] informal a medical condition in which a type of ↑louse (=insect) is in the hair around sexual organs
4. [singular] American English informal someone who becomes annoyed easily about unimportant things
Oxford Advanced Learner's Dictionary
crab
crab [crab crabs crabbed crabbing] [kræb] [kræb] noun
1. countable a sea creature with a hard shell, eight legs and two pincers (= curved and pointed arms for catching and holding things). Crabs move sideways on land.
see also hermit crab
2. uncountable meat from a crab, used for food
• dressed crab
3. crabs (informal) the condition caused by having lice (called crab lice) in the hair around the genitals
Word Origin:
Old English crabba, of Germanic origin; related to Dutch krabbe, and more distantly to Dutch kreeft and German Krebs; also to crab in the sense to grumble.
Cambridge Advanced Learner's Dictionary
Cambridge Advanced Learner's Dictionary - 4th Edition
crab / kræb / noun [ C or U ] (SEA CREATURE)
B2 a sea creature with five pairs of legs and a round, flat body covered by a shell, or its flesh eaten as food:
We walked along the beach collecting small crabs.
All the shops on the seafront had crab for sale.
This crab meat/salad is delicious!
crab / kræb / noun [ C or U ] (DISEASE)
crabs [ plural ] ( also ˈ crab lice )
small insects that can live in the hair around the sex organs
© Cambridge University Press 2013
Collins Advanced Learner’s English Dictionary
crab
/kræb/
(crabs)
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.
N-COUNT
Crab is the flesh of this creature eaten as food.
N-UNCOUNT
Merriam-Webster's Advanced Learner's Dictionary
1crab /ˈkræb/ noun, pl crabs
1 a [count] : a sea animal that has a hard shell, eight legs, and two large claws - see color picture
- see also hermit crab, king crab
b [noncount] : the meat of a crab eaten as food
• We had crab for dinner.
2 crabs [plural] medical : a medical problem in which very small insects (called lice) live in the hair surrounding a person's sexual organs
3 [count] US informal : an unhappy person who complains a lot : grouch
• I don't know why she's been such a crab lately.