The Collaborative International Dictionary of English v.0.48:

Tangent wheel \Tangent wheel\
   (a) A worm or worm wheel; a tangent screw.
   (b) A wheel with tangent spokes.
       [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Worm \Worm\ (w[^u]rm), n. [OE. worm, wurm, AS. wyrm; akin to D.
   worm, OS. & G. wurm, Icel. ormr, Sw. & Dan. orm, Goth.
   wa['u]rms, L. vermis, Gr. ? a wood worm. Cf. Vermicelli,
   Vermilion, Vermin.]
   [1913 Webster]
   1. A creeping or a crawling animal of any kind or size, as a
      serpent, caterpillar, snail, or the like. [Archaic]
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            There came a viper out of the heat, and leapt on his
            hand. When the men of the country saw the worm hang
            on his hand, they said, This man must needs be a
            murderer.                             --Tyndale
                                                  (Acts xxviii.
                                                  3, 4).
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            'T is slander,
            Whose edge is sharper than the sword, whose tongue
            Outvenoms all the worms of Nile.      --Shak.
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            When Cerberus perceived us, the great worm,
            His mouth he opened and displayed his tusks.
                                                  --Longfellow.
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   2. Any small creeping animal or reptile, either entirely
      without feet, or with very short ones, including a great
      variety of animals; as, an earthworm; the blindworm.
      Specifically: (Zool.)
      (a) Any helminth; an entozoon.
      (b) Any annelid.
      (c) An insect larva.
      (d) pl. Same as Vermes.
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   3. An internal tormentor; something that gnaws or afflicts
      one's mind with remorse.
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            The worm of conscience still begnaw thy soul!
                                                  --Shak.
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   4. A being debased and despised.
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            I am a worm, and no man.              --Ps. xxii. 6.
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   5. Anything spiral, vermiculated, or resembling a worm; as:
      (a) The thread of a screw.
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                The threads of screws, when bigger than can be
                made in screw plates, are called worms. --Moxon.
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      (b) A spiral instrument or screw, often like a double
          corkscrew, used for drawing balls from firearms.
      (c) (Anat.) A certain muscular band in the tongue of some
          animals, as the dog; the lytta. See Lytta.
      (d) The condensing tube of a still, often curved and wound
          to economize space. See Illust. of Still.
      (e) (Mach.) A short revolving screw, the threads of which
          drive, or are driven by, a worm wheel by gearing into
          its teeth or cogs. See Illust. of Worm gearing,
          below.
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   Worm abscess (Med.), an abscess produced by the irritation
      resulting from the lodgment of a worm in some part of the
      body.

   Worm fence. See under Fence.

   Worm gear. (Mach.)
      (a) A worm wheel.
      (b) Worm gearing.

   Worm gearing, gearing consisting of a worm and worm wheel
      working together.

   Worm grass. (Bot.)
      (a) See Pinkroot, 2
      (a) .
      (b) The white stonecrop (Sedum album) reputed to have
          qualities as a vermifuge. --Dr. Prior.

   Worm oil (Med.), an anthelmintic consisting of oil obtained
      from the seeds of Chenopodium anthelminticum.

   Worm powder (Med.), an anthelmintic powder.

   Worm snake. (Zool.) See Thunder snake
      (b), under Thunder.

   Worm tea (Med.), an anthelmintic tea or tisane.

   Worm tincture (Med.), a tincture prepared from dried
      earthworms, oil of tartar, spirit of wine, etc. [Obs.]

   Worm wheel, a cogwheel having teeth formed to fit into the
      spiral spaces of a screw called a worm, so that the wheel
      may be turned by, or may turn, the worm; -- called also
      worm gear, and sometimes tangent wheel. See Illust. of
      Worm gearing, above.
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