The word 'weakness' is a transparent Germanic compound. Its core, 'weak', descends from the Old English wāc, which carried meanings of being pliant, yielding, or lacking physical force. This term is part of a wider Germanic family, related to Old Norse veikr and Dutch week. The suffix '-ness' is one of the most productive noun-forming elements in English, directly inherited from the Old English -nes, which denoted an abstract state or condition. Therefore, the literal construction "the state of being weak" has remained semantically stable from its Old English origins to its modern usage, where it describes both physical lack of strength and metaphorical flaws or vulnerabilities.

Structure: weak (lacking strength) + ness (state or quality) - weak: From Old English wāc (pliant, yielding, weak), of Germanic origin. Functions as the core adjective root describing the quality. - ness: From Old English -nes, -ness, a suffix forming nouns of state or quality, from Proto-Germanic. Functions as a nominalizing suffix.