The Oxford Thesaurus An A-Z Dictionary of Synonyms - frailty n.

1) weakness, infirmity, delicate condition, feebleness, fragility, delicacy: The doctors are concerned about his frailty. 2) susceptibility, liability, suggestibility, impressionability, vulnerability; fallibility, foible, flaw, defect, imperfection, fault: You just said that to take advantage of my frailty. Her vanity is her greatest frailty.