The Collaborative International Dictionary of English v.0.48:

Shear \Shear\, v. i.
   1. To deviate. See Sheer.
      [1913 Webster]

   2. (Engin.) To become more or less completely divided, as a
      body under the action of forces, by the sliding of two
      contiguous parts relatively to each other in a direction
      parallel to their plane of contact.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Shear \Shear\, n. [AS. sceara. See Shear, v. t.]
   1. A pair of shears; -- now always used in the plural, but
      formerly also in the singular. See Shears.
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            On his head came razor none, nor shear. --Chaucer.
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            Short of the wool, and naked from the shear.
                                                  --Dryden.
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   2. A shearing; -- used in designating the age of sheep.
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            After the second shearing, he is a two-shear ram; .
            . . at the expiration of another year, he is a
            three-shear ram; the name always taking its date
            from the time of shearing.            --Youatt.
      [1913 Webster]

   3. (Engin.) An action, resulting from applied forces, which
      tends to cause two contiguous parts of a body to slide
      relatively to each other in a direction parallel to their
      plane of contact; -- also called shearing stress, and
      tangential stress.
      [1913 Webster]

   4. (Mech.) A strain, or change of shape, of an elastic body,
      consisting of an extension in one direction, an equal
      compression in a perpendicular direction, with an
      unchanged magnitude in the third direction.
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   Shear blade, one of the blades of shears or a shearing
      machine.

   Shear hulk. See under Hulk.

   Shear steel, a steel suitable for shears, scythes, and
      other cutting instruments, prepared from fagots of
      blistered steel by repeated heating, rolling, and tilting,
      to increase its malleability and fineness of texture.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Shear \Shear\ (sh[=e]r), v. t. [imp. Shearedor Shore;p. p.
   Sheared or Shorn; p. pr. & vb. n. Shearing.] [OE.
   sheren, scheren, to shear, cut, shave, AS. sceran, scieran,
   scyran; akin to D. & G. scheren, Icel. skera, Dan. ski?re,
   Gr. ???. Cf. Jeer, Score, Shard, Share, Sheer to
   turn aside.]
   1. To cut, clip, or sever anything from with shears or a like
      instrument; as, to shear sheep; to shear cloth.
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   Note: It is especially applied to the cutting of wool from
         sheep or their skins, and the nap from cloth.
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   2. To separate or sever with shears or a similar instrument;
      to cut off; to clip (something) from a surface; as, to
      shear a fleece.
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            Before the golden tresses . . . were shorn away.
                                                  --Shak.
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   3. To reap, as grain. [Scot.] --Jamieson.
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   4. Fig.: To deprive of property; to fleece.
      [1913 Webster]

   5. (Mech.) To produce a change of shape in by a shear. See
      Shear, n., 4.
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WordNet (r) 3.0 (2006):

shear
    n 1: (physics) a deformation of an object in which parallel
         planes remain parallel but are shifted in a direction
         parallel to themselves; "the shear changed the
         quadrilateral into a parallelogram"
    2: a large edge tool that cuts sheet metal by passing a blade
       through it
    v 1: cut with shears; "shear hedges"
    2: shear the wool from; "shear sheep" [syn: fleece, shear]
    3: cut or cut through with shears; "shear the wool off the lamb"
    4: become deformed by forces tending to produce a shearing
       strain