The word 'strength' originates from the Old English 'strengþu', which itself evolved from the earlier adjective 'strang' (strong). The core element 'streng-' is of Proto-Germanic origin, related to the concept of tightness, severity, and power. The addition of the abstract noun suffix '-th' (from Proto-Germanic '-itho') transformed the adjective into a noun denoting the quality or state of being strong. This morphological process, common in Germanic languages, gave English a direct and enduring term for physical power, resilience, and moral fortitude.

Structure: streng (strong) + th (noun suffix) 'streng' is from Old English 'streng', meaning strong or powerful, derived from Proto-Germanic. 'th' is a noun-forming suffix from Old English '-þu', '-þo', '-þ', used to form abstract nouns from adjectives.