frailty

1. The condition or quality of being frail.
2. A fault, especially a moral weakness.

noun

1. The condition of being infirm or physically weak: debility, decrepitude, delicacy, delicateness, feebleness, flimsiness, fragileness, fragility, frailness, infirmity, insubstantiality, puniness, unsoundness, unsubstantiality, weakliness, weakness. See strong/weak.
2. An imperfection of character: failing, fault, foible, infirmity, shortcoming, weakness, weak point. See better/worse, help/harm/harmless.

Definition: weakness, flaw
Antonyms: firmness, strength

The noun has 2 meanings:

Meaning #1: the state of being weak in health or body (especially from old age)
  Synonyms: infirmity, debility, feebleness, frailness

Meaning #2: moral weakness
  Synonym: vice