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• crab
  crab

  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
  Crab

  noun

  the constellation Cancer, the fourth sign of the zodiac

crab

¹ American  

[krab] / kræb /

noun

1. 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.

2. any of various other crustaceans, as the hermit crab, or other animals, as the horseshoe crab, resembling the true crabs.

3. Crab,

   1. Astronomy, Astrology. the zodiacal constellation or sign Cancer.

   2. Astronomy. the Crab Nebula.

4. any of various mechanical contrivances for hoisting or pulling.

5. Aeronautics. the maneuver of crabbing.

6. Informal. the crab louse. louse1

7. crabs,

   1. (used with a singular verb) a losing throw, as two aces, in the game of hazard.

   2. pediculosis.

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verb (used without object)

crabbed, crabbing

1. to catch or attempt to catch crabs.

2. to move sideways, diagonally, or obliquely, especially with short, abrupt bursts of speed; scuttle.

3. Aeronautics. (of an aircraft) to head partly into the wind to compensate for drift.

4. Nautical. to drift or advance with some movement sideways, especially when under tow.

verb (used with object)

crabbed, crabbing

1. to move (a vehicle or object) sideways, diagonally, or obliquely, especially with short, abrupt movements.

2. Aeronautics. to head (an aircraft) partly into the wind to compensate for drift.

idioms

1. catch a crab, to make a faulty stroke in rowing, so that the oar strikes the water forcibly on the backstroke.

crab ² American  

[krab] / kræb /

noun

1. a crab apple fruit or tree.

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crab ³ American  

[krab] / kræb /

noun

1. Informal. an ill-tempered or grouchy person.

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verb (used without object)

crabbed, crabbing

1. Informal. to find fault; complain.

2. (of hawks) to claw each other.

verb (used with object)

crabbed, crabbing

1. Informal. to find fault with.

2. to make ill-tempered or grouchy; embitter.

3. (of a hawk) to claw (another hawk).

4. Slang. to spoil.

crab ¹ British  

/ kræb /

noun

1. 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 See also fiddler crab soft-shell crab pea crab oyster crab

2. any of various similar or related arthropods, such as the hermit crab and horseshoe crab

3. short for crab louse

4. a manoeuvre in which an aircraft flies slightly into the crosswind to compensate for drift

5. a mechanical lifting device, esp the travelling hoist of a gantry crane

6. wrestling See Boston crab

7. rowing to make a stroke in which the oar either misses the water or digs too deeply, causing the rower to fall backwards

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verb

1. (intr) to hunt or catch crabs

2. (tr) to fly (an aircraft) slightly into a crosswind to compensate for drift

3. (intr) nautical to move forwards with a slight sideways motion, as to overcome an offsetting current

4. (intr) to move sideways

crab ² British  

/ kræb /

verb

1. (intr) to find fault; grumble

2. (tr) to spoil (esp in the phrase crab someone's act )

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noun

1. an irritable person

2. to attract unwelcome attention

Crab ³ British  

/ kræb /

noun

1. the constellation Cancer, the fourth sign of the zodiac

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crab ⁴ British  

/ kræb /

noun

1. short for crab apple

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Other Word Forms

Derived Forms

• crabber
  noun
• crablike
  adjective

Etymology

Origin of crab¹

First recorded before 1000; Middle English crabbe, Old English crabba; cognate with Dutch krab, Old Norse krabbi; akin to German Krebs

Origin of crab²

First recorded in 1300–50; Middle English crabbe; perhaps special use of crab ¹

Origin of crab³

First recorded in 1350–1400; Middle English; back formation from crabbed

Explanation

A crab is a stubby sea creature with a flat body, eight legs, and claws. You can sometimes find tiny crabs in the sand on the beach. Crabs have a thick, shell-like covering called an "exoskeleton," and you can find them in both fresh and saltwater. Some types of crab are considered a delicacy, with sweet, delicate flesh often called "crab meat." There are many shelled sea creatures with crab in their names, like horseshoe crabs and hermit crabs, that aren't true crabs. The word crab comes from a Germanic root related to the Low German krabben, "to claw."

Example Sentences

The criteria for diagnosing myeloma are sometimes described using the acronym CRAB: Calcium elevation, Renal issues, Anemia, Bone problems.

From Slate • Mar. 29, 2026

Yet carbapenem-resistant Acinetobacter baumannii, or CRAB, is a nightmare for hospitals worldwide, as it kills roughly half of all patients who acquire it.

From Los Angeles Times • Jan. 3, 2024

CRAB, which offers individual and group lessons, family sailing events and competitive regattas, can accommodate pretty much any kind of disability, Bollinger said: blindness, deafness, autism, muscular dystrophy, “really anything you can think of.”

From Washington Post • Oct. 4, 2019

“The raft will not be named the CRAB, either, it seems,” said Nyoda.

From The Camp Fire Girls at Onoway House or, The Magic Garden by Frey, Hildegard G. (Hildegard Gertrude)

CRAB, the.—What it is to think as a crab walks, 295.

From The Delights of Wisdom Pertaining to Conjugial Love by Swedenborg, Emanuel