tooth

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One of a set of hard, bonelike structures in the jaws of vertebrates, usually rooted in sockets and 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.
• noun A similar hard projection in an invertebrate, such as one of a set of projections on the hinge of a bivalve or on the radula of a snail.
• noun A projecting part resembling a tooth in shape or function, as on a comb, gear, or saw.
• noun A small, notched projection along a margin, especially of a leaf.
• noun A rough surface, as of paper or metal.
• noun Something that injures or destroys with force.
• noun Effective means of enforcement; muscle.
• intransitive verb To furnish (a tool, for example) with teeth.
• intransitive verb To make a jagged edge on.
• intransitive verb To become interlocked; mesh.
• idiom (get/sink) To be actively involved in; get a firm grasp of.
• idiom (show/bare) To express a readiness to fight; threaten defiantly.
• idiom (to the teeth) Lacking nothing; completely.

from The Century Dictionary.

• noun A hard (horny, dentinal, osseous, chitinous, calcareous, or silicious) body or substance, in the mouth, pharynx, gullet, or stomach of an animal, serving primarily for the apprehension, mastication, or trituration of food, and secondarily as a weapon of attack or defense, and for a variety of other purposes, as digging in the ground, climbing, articulation of vocal sounds, etc.
• noun In Invertebrata, one of various hard bodies, presenting great variety of position and structure, which may occur in the alimentary canal from the month to the stomach.
• noun In zoology, a projection resembling or likened to a tooth.
• noun In botany, any small pointed marginal lobe, especially of a leaf: in mosses applied to the delicate fringe of processes about the mouth of the capsule, collectively known as the peristome. See peristome, Musci, and cuts under cilium and Dicranum.
• noun Any projection corresponding to or resembling the tooth of an animal in shape, position, or office; a small, narrow, projecting piece, usually one of a set.
• noun One of the tines or prongs of a fork.
• noun One of the sharp wires of a carding-instrument.
• noun One of a series of projections on the edge of a wheel which catch on corresponding parts of a wheel or other body; a cog. See cut under pinion.
• noun plural In a rose-cut diamond, the lower zone of facets. They form a truncated cone-shaped base for the crown.
• noun In veneering, the roughness made by the toothing-plane on the surfaces to be glued together to afford a good hold for the glue.
• noun Figuratively, a fang; the sharp or distressing part of anything.
• noun Palate; relish; taste, literally or figuratively. Compare a sweet tooth, below.
• noun Keep; maintenance.
• noun To one's face; openly.
• noun Straight against: noting direction: as, to walk in the teeth of the wind.
• noun In the face or presence of; before.
• noun The processes or serration of the mandibles of any insect, as a stag-beetle.
• noun The topography of the tooth, as now described, is shown in the cuts.
• noun A roughened surface, as of a paper prepared for pastels.
• noun In masonry, one of the several projecting ends of stones or bricks already built into a wall and left at an unfinished end of it to facilitate the fitting of another piece of wall to the first one.
• To bite; taste.
• To furnish with teeth: as, to tooth a rake.
• To indent; cut into teeth; jag.
• To lock one in another.
• To teethe.
• To interlock, as cog-wheels.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To furnish with teeth.
• transitive verb To indent; to jag.
• transitive verb To lock into each other. See Tooth, n., 4.
• noun (Anat.) One of the hard, bony appendages which are borne on the jaws, or on other bones in the walls of the mouth or pharynx of most vertebrates, and which usually aid in the prehension and mastication of food.
• noun Fig.: Taste; palate.
• noun Any projection corresponding to the tooth of an animal, in shape, position, or office.
• noun A projecting member resembling a tenon, but fitting into a mortise that is only sunk, not pierced through.
• noun One of several steps, or offsets, in a tusk. See Tusk.