The Collaborative International Dictionary of English v.0.48:

Strength \Strength\, n. [OE. strengthe, AS. streng[eth]u, fr.
   strang strong. See Strong.]
   1. The quality or state of being strong; ability to do or to
      bear; capacity for exertion or endurance, whether
      physical, intellectual, or moral; force; vigor; power; as,
      strength of body or of the arm; strength of mind, of
      memory, or of judgment.
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            All his [Samson's] strength in his hairs were.
                                                  --Chaucer.
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            Thou must outlive
            Thy youth, thy strength, thy beauty.  --Milton.
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   2. Power to resist force; solidity or toughness; the quality
      of bodies by which they endure the application of force
      without breaking or yielding; -- in this sense opposed to
      frangibility; as, the strength of a bone, of a beam, of
      a wall, a rope, and the like. "The brittle strength of
      bones." --Milton.
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   3. Power of resisting attacks; impregnability. "Our castle's
      strength will laugh a siege to scorn." --Shak.
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   4. That quality which tends to secure results; effective
      power in an institution or enactment; security; validity;
      legal or moral force; logical conclusiveness; as, the
      strength of social or legal obligations; the strength of
      law; the strength of public opinion; strength of evidence;
      strength of argument.
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   5. One who, or that which, is regarded as embodying or
      affording force, strength, or firmness; that on which
      confidence or reliance is based; support; security.
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            God is our refuge and strength.       --Ps. xlvi. 1.
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            What they boded would be a mischief to us, you are
            providing shall be one of our principal strengths.
                                                  --Sprat.
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            Certainly there is not a greater strength against
            temptation.                           --Jer. Taylor.
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   6. Force as measured; amount, numbers, or power of any body,
      as of an army, a navy, and the like; as, what is the
      strength of the enemy by land, or by sea?
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   7. Vigor or style; force of expression; nervous diction; --
      said of literary work.
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            And praise the easy vigor of a life
            Where Denham's strength and Waller's sweetness join.
                                                  --Pope.
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   8. Intensity; -- said of light or color.
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            Bright Phoebus in his strength.       --Shak.
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   9. Intensity or degree of the distinguishing and essential
      element; spirit; virtue; excellence; -- said of liquors,
      solutions, etc.; as, the strength of wine or of acids.
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   10. A strong place; a stronghold. [Obs.] --Shak.
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   On the strength of, or Upon the strength of, in reliance
      upon. "The allies, after a successful summer, are too apt,
      upon the strength of it, to neglect their preparations for
      the ensuing campaign." --Addison.
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   Syn: Force; robustness; toughness; hardness; stoutness;
        brawniness; lustiness; firmness; puissance; support;
        spirit; validity; authority. See Force.
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The Collaborative International Dictionary of English v.0.48:

Strength \Strength\, v. t.
   To strengthen. [Obs.] --Chaucer.
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WordNet (r) 3.0 (2006):

strength
    n 1: the property of being physically or mentally strong;
         "fatigue sapped his strength" [ant: weakness]
    2: capability in terms of personnel and materiel that affect the
       capacity to fight a war; "we faced an army of great
       strength"; "politicians have neglected our military posture"
       [syn: military capability, military strength, strength,
       military posture, posture]
    3: physical energy or intensity; "he hit with all the force he
       could muster"; "it was destroyed by the strength of the
       gale"; "a government has not the vitality and forcefulness of
       a living man" [syn: force, forcefulness, strength]
    4: an asset of special worth or utility; "cooking is his forte"
       [syn: forte, strong suit, long suit, metier,
       specialty, speciality, strong point, strength] [ant:
       weak point]
    5: the power to induce the taking of a course of action or the
       embracing of a point of view by means of argument or
       entreaty; "the strength of his argument settled the matter"
       [syn: persuasiveness, strength] [ant: unpersuasiveness]
    6: the amount of energy transmitted (as by acoustic or
       electromagnetic radiation); "he adjusted the intensity of the
       sound"; "they measured the station's signal strength" [syn:
       intensity, strength, intensity level]
    7: capacity to produce strong physiological or chemical effects;
       "the toxin's potency"; "the strength of the drinks" [syn:
       potency, effectiveness, strength]
    8: the condition of financial success; "the strength of the
       company's stock in recent weeks" [ant: weakness]
    9: permanence by virtue of the power to resist stress or force;
       "they advertised the durability of their products" [syn:
       lastingness, durability, enduringness, strength]