The Collaborative International Dictionary of English v.0.48:

Tension \Ten"sion\, n. [L. tensio, from tendere, tensum, to
   stretch: cf. F. tension. See Tense, a.]
   1. The act of stretching or straining; the state of being
      stretched or strained to stiffness; the state of being
      bent strained; as, the tension of the muscles, tension of
      the larynx.
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   2. Fig.: Extreme strain of mind or excitement of feeling;
      intense effort.
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   3. The degree of stretching to which a wire, cord, piece of
      timber, or the like, is strained by drawing it in the
      direction of its length; strain. --Gwilt.
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   4. (Mech.) The force by which a part is pulled when forming
      part of any system in equilibrium or in motion; as, the
      tension of a srting supporting a weight equals that
      weight.
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   5. A device for checking the delivery of the thread in a
      sewing machine, so as to give the stitch the required
      degree of tightness.
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   6. (Physics) Expansive force; the force with which the
      particles of a body, as a gas, tend to recede from each
      other and occupy a larger space; elastic force;
      elasticity; as, the tension of vapor; the tension of air.
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   7. (Elec.) The quality in consequence of which an electric
      charge tends to discharge itself, as into the air by a
      spark, or to pass from a body of greater to one of less
      electrical potential. It varies as the quantity of
      electricity upon a given area.
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   Tension brace, or Tension member (Engin.), a brace or
      member designed to resist tension, or subjected to
      tension, in a structure.

   Tension rod (Engin.), an iron rod used as a tension member
      to strengthen timber or metal framework, roofs, or the
      like.
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