Jonah \Jo"nah\, n. The Hebrew prophet, who was cast overboard as one who endangered the ship; hence, any person whose presence is unpropitious.

Jonah crab (Zo["o]l.), a large crab (Cancer borealis) of the eastern coast of the United States, sometimes found between tides, but usually in deep water.

Source: Webster's Revised Unabridged Dictionary (1913)