The definition of strength is power, potency or toughness.(noun)
See strength in Webster's New World College Dictionary
Origin: ME strengthe < OE strengthu < *strang-ithu: see strong & -th
See strength in American Heritage Dictionary 4
Origin: Middle English
Origin: , from Old English strengthu. Usage Note: Although the word strength is not spelled with a k, it is most often pronounced (strĕngkth), 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 (strĕnth), 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.
Learn more about strength