Crab meaning : A crustacean of the infraorder Brachyura, having five pairs of legs, the foremost of which are in the form of claws, and a carapace. The meat of this crustacean, served as food; crabmeat A bad-tempered person. (in plural crabs) An infestation of pubic lice (Pthirus pubis). A playing card with the rank of three. A position in rowing where the oar is pushed under the rigger by the force of the water. A defect in an outwardly normal object that may render it inconvenient and troublesome to use. An unsold book that is returned to the publisher. To fish for crabs. To ruin. To complain. To drift or move sideways or to leeward (by analogy with the movement of a crab). To navigate (an aircraft, e.g. a glider) sideways against an air current in order to maintain a straight-line course. To move (a camera) sideways. (World War I), to fly slightly off the straight-line course towards an enemy aircraft, as the machine guns on early aircraft did not allow firing through the propeller disk. To back out of something.