Source : Webster's Revised Unabridged Dictionary (1913)

Strength \Strength\, v. t.
   To strengthen. [Obs.] --Chaucer.

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.

            All his [Samson's] strength in his hairs were.
                                                  --Chaucer.

            Thou must outlive Thy youth, thy strength, thy
            beauty.                               --Milton.

   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.

   3. Power of resisting attacks; impregnability. ``Our castle's
      strength will laugh a siege to scorn.'' --Shak.

   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.

   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.

            God is our refuge and strength.       --Ps. xlvi. 1.

            What they boded would be a mischief to us, you are
            providing shall be one of our principal strengths.
                                                  --Sprat.

            Certainly there is not a greater strength against
            temptation.                           --Jer. Taylor.

   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?

   7. Vigor or style; force of expression; nervous diction; --
      said of literary work.

            And praise the easy vigor of a life Where Denham's
            strength and Waller's sweetness join. --Pope.

   8. Intensity; -- said of light or color.

            Bright Ph[oe]bus in his strength.     --Shak.

   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.

   10. A strong place; a stronghold. [Obs.] --Shak.

   {On}, 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.

   Syn: Force; robustness; toughness; hardness; stoutness;
        brawniness; lustiness; firmness; puissance; support;
        spirit; validity; authority. See {Force}.

Source : WordNet®

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},
         {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}]
     4: an asset of special worth or utility; "cooking is his forte"
        [syn: {forte}, {strong suit}, {long suit}, {metier}, {specialty},
         {speciality}, {strong point}] [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}] [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}, {intensity level}]
     7: capacity to produce strong physiological or chemical
        effects; "the toxin's potency"; "the strength of the
        drinks" [syn: {potency}, {effectiveness}]
     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}]