1. One of a set of hard, bonelike structures rooted in sockets in the jaws of vertebrates (including humans), typically composed of a core of soft pulp surrounded by a layer of hard dentin that is coated with cementum or enamel at the crown and used for biting or chewing food or as a means of attack or defense.
2. A sharp part on an invertebrate made of horny, calcareous, or chitinous material and functioning like or resembling a vertebrate tooth.
3. An object with the shape or function of a tooth; such as, one of the jagged indentations along the edge of a saw or leaf.
4. A part that sticks out from the edge of a gear wheel or sprocket, designed to interlock with a similar part on another wheel.
5. The roughness of a surface, especially that of paper, which allows paints, glues, and other substances to stick to it.
6. A liking for the taste of something; such as, having a "sweet tooth".
7. Something that has the power to destroy; usually used in the plural: "They were caught in the teeth of the gale."

More about the tooth and the teeth

The structures within the mouth that allow for biting and chewing. Teeth have different shapes, depending on their purpose.

• The sharp canine and frontal teeth allow for biting, while the flattened, thick molars in the back of the mouth provide grinding surfaces for masticating food.
• All teeth have essentially the same structure: a hard crown above the gum line, which is attached to two or four roots by a portion called the neck.
• The roots are covered with a very thin layer of bone, and keep the tooth embedded in the bones of the jaw.
• The exposed exterior of the tooth is covered with tough enamel.
• Under the enamel is a thick layer of dentin, and in the center is the pulp.
• Blood vessels and nerves are found within the pulp.