The Collaborative International Dictionary of English v.0.48:

frailty \frail"ty\ (fr[=a]l"t[y^]), n.; pl. frailties
   (fr[=a]l"t[i^]z). [OE. frelete, freilte, OF. frailet['e], fr.
   L. fragilitas. See Frail, a., and cf. Fragility.]
   1. The condition or quality of being frail, physically,
      mentally, or morally; frailness; infirmity; weakness of
      resolution; liableness to be deceived or seduced.
      [1913 Webster]

            God knows our frailty, [and] pities our weakness.
                                                  --Locke.
      [1913 Webster]

   2. A fault proceeding from weakness; foible; sin of
      infirmity.

   Syn: Frailness; fragility; imperfection; failing.
        [1913 Webster]

WordNet (r) 3.0 (2006):

frailty
    n 1: the state of being weak in health or body (especially from
         old age) [syn: infirmity, frailty, debility,
         feebleness, frailness, valetudinarianism]
    2: moral weakness [syn: frailty, vice]