S: (n) weakness (the property of lacking physical or mental strength; liability to failure under pressure or stress or strain) "his weakness increased as he became older"; "the weakness of the span was overlooked until it collapsed"
S: (n) smallness, littleness (the property of having relatively little strength or vigor) "the smallness of her voice"
S: (n) adynamia (lack of strength or vigor (especially from illness))
S: (n) feebleness, tenuity (the quality of lacking intensity or substance) "a shrill yet sweet tenuity of voice"- Nathaniel Hawthorne
S: (n) faintness (the property of being without strength) "the faintness or potency of the feeling"