Definitions of crab:

• noun:   a stroke of the oar that either misses the water or digs too deeply

  Example: "He caught a crab and lost the race"

• noun:   decapod having eyes on short stalks and a broad flattened carapace with a small abdomen folded under the thorax and pincers
• noun:   the edible flesh of any of various crabs
• noun:   a quarrelsome grouch
• noun:   (astrology) a person who is born while the sun is in Cancer
• noun:   infests the pubic region of the human body
• noun:   the fourth sign of the zodiac; the sun is in this sign from about June 21 to July 22
• verb:   fish for crab
• verb:   scurry sideways like a crab
• verb:   direct (an aircraft) into a crosswind
• verb:   complain