What is the meaning of mole?

noun

• The molecular weight of a substance expressed in grams; the basic unit of amount of substance adopted under the Systeme International d'Unites.
  • synonyms: gram molecule, mol
• A spy who works against enemy espionage.
  • synonyms: counterspy
• Spicy sauce often containing chocolate.
• A small congenital pigmented spot on the skin.
• A protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away.
  • synonyms: breakwater, groin, groyne, bulwark, seawall, jetty
• Small velvety-furred burrowing mammal having small eyes and fossorial forefeet. .