A crab is any of various crustaceans with four pairs of legs, a pair of pincers, a flattish shell, and a short, broad abdomen folded under its thorax. Several similar animals, such as the crab louse, or the hermit crab[?], are also called crabs.
A crab is any of various machines used to hoist heavy objects.
... gyroscope, with a maximum effect when the axis starts "rolling" inside the groove. (Compare with graphic below.) Since this friction force is essential for the device's ...