Clove (Eugenia caryophyllata also sometimes Syzygium aromaticum, Myrtaceae) is an aromatic spice made from the dried buds of a tree native to Indonesia, and still grown there as well as in Madagascar. The name derives from French clou, a nail, as the buds vaguely resemble small irregular nails in shape. Cloves can be used in cooking either whole or in a ground form, but they are extremely strong so use them with caution.
Essential oil of clove has anesthetic and antimicrobial qualities, and is sometimes used to ameliorate the pain of a bad tooth. It, or its main component eugenol, is used by dentists to anesthetize the gum before injecting Novocaine or similar anesthetics, and is the characteristic odor of a dentist's office.
see also the Wikipedia Cookbook