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.
The spice is used throughout Europe and Asia and is smoked in cigarettes in Indonesia and in occasional coffee bars in the west.
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.
The word clove is also used to describe a segment of a head of garlic and a clove hitch is a useful kind of knot.
see also the Wikipedia Cookbook