nail

noun

• The thin, horny plate at the ends of fingers and toes on humans and some other animals.

  "When I'm nervous I bite my nails."

• The basal thickened portion of the anterior wings of certain hemiptera.
• The terminal horny plate on the beak of ducks, and other allied birds.
• The claw of a bird or other animal.
• A spike-shaped metal fastener used for joining wood or similar materials. The nail is generally driven through two or more layers of material by means of impacts from a hammer or other device. It is then held in place by friction.
• A round pedestal on which merchants once carried out their business, such as the four nails outside The Exchange, Bristol.
• An archaic English unit of length equivalent to 1/20 of an ell or 1/16 of a yard (2 1/4 inches or 5.715 cm).