1. The state, property, or quality of being strong.
2. The power to resist attack; impregnability.
3. The power to resist strain or stress; durability.
4. The ability to maintain a moral or intellectual position firmly.
5. Capacity or potential for effective action: a show of strength.
6. 1. The number of people constituting a normal or ideal organization: The police force has been at half strength since the budget cuts.
   2. Military capability in terms of personnel and materiel: an army of fearsome strength.
   3. A source of power or force.
   4. One that is regarded as the embodiment of protective or supportive power; a support or mainstay.
   5. An attribute or quality of particular worth or utility; an asset.
   6. Degree of concentration, distillation, or saturation; potency.
   7. Operative effectiveness or potency.
   8. Intensity, as of sound or light.
   9. Intensity or vehemence, as of emotion or language.
7. 1. A source of power or force.
   2. One that is regarded as the embodiment of protective or supportive power; a support or mainstay.
   3. An attribute or quality of particular worth or utility; an asset.
   4. Degree of concentration, distillation, or saturation; potency.
   5. Operative effectiveness or potency.
   6. Intensity, as of sound or light.
   7. Intensity or vehemence, as of emotion or language.
8. Degree of intensity, force, effectiveness, or potency in terms of a particular property, as:
   1. Degree of concentration, distillation, or saturation; potency.
   2. Operative effectiveness or potency.
   3. Intensity, as of sound or light.
   4. Intensity or vehemence, as of emotion or language.
9. Effective or binding force; efficacy: the strength of an argument.
10. Firmness of or a continuous rising tendency in prices, as on the stock market.
11. Games Power derived from the value of playing cards held.

Synonyms: These nouns denote the capacity to act or work effectively. Strength refers especially to physical, mental, or moral robustness or vigor: "enough work to do, and strength enough to do the work" (Rudyard Kipling).
Power is the ability to do something and especially to produce an effect: "I do not think the United States would come to an end if we lost our power to declare an Act of Congress void" (Oliver Wendell Holmes, Jr.)
Might often implies abundant or extraordinary power: "He could defend the island against the whole might of the German Air Force" (Winston S. Churchill).
Energy refers especially to a latent source of power: "The same energy of character which renders a man a daring villain would have rendered him useful to society, had that society been well organized" (Mary Wollstonecraft).
Force is the application of power or strength: "the overthrow of our institutions by force and violence" (Charles Evans Hughes).

Usage Note: Although the word strength is not spelled with a k, it is most often pronounced (strěngkth), with a (k) sound inserted between the (ng) and the (th). This intrusive (k) occurs for a simple reason: In making the transition from the voiced velar nasal (ng) to the voiceless dental fricative (th), speakers naturally produce the voiceless velar stop (k), which is made at the same place in the mouth as (ng) but is voiceless like (th). Other words with intrusive consonants include warmth, which may sound like it is spelled warmpth, and prince, which may sound like prints. The pronunciation (strěnth), which is made with (n) before (th), arises by the phonological process of assimilation. The velar (ng) moves forward in the mouth, becoming (n) before (th), which is made at the front of the mouth. Criticized in the past as sloppy, this pronunciation is now generally regarded as a standard, although less common, variant. The similar pronunciation of length is now also considered acceptable.