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tooth (tth)
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n. pl. teeth (tēth)
1.
a. One of a set of hard, bonelike structures in the mouths of vertebrates, usually attached to the jaw or 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.
b. 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.
2. A projecting part resembling a tooth in shape or function, as on a comb, gear, or saw.
3. A small, notched projection along a margin, especially of a leaf. Also called dent2.
4. A rough surface, as of paper or metal.
5.
a. often teeth Something that injures or destroys with force: the teeth of the blizzard.
b. teeth Effective means of enforcement; muscle: "This ... puts real teeth into something where there has been only lip service" (Ellen Convisser).
v. (tth, tth) toothed, tooth·ing, tooths
v.tr.
1. To furnish (a tool, for example) with teeth.
2. To make a jagged edge on.
v.intr.
To become interlocked; mesh.
Idioms:
get/sink (one's) teeth into Slang
To be actively involved in; get a firm grasp of.
show/bare (one's) teeth
To express a readiness to fight; threaten defiantly.
to the teeth
Lacking nothing; completely: armed to the teeth; dressed to the teeth.

[Middle English toth, from Old English tōth; see dent- in the Appendix of Indo-European roots.]
(click for a larger image)
tooth
top: cross section of a human tooth
bottom: teeth on mechanical gears

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

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