assailability, blemish, bug, catch, chink, crack, defect, defection, deficiency, drawback, failing, failure, fault, faute, flaw, foible, frailty, heel of Achilles, hole, imperfection, inadequacy, infirmity, kink, little problem, penetrability, pregnability, problem, rift, shortcoming, snag, soft spot, something missing, taint, vincibility, vulnerability, vulnerable place, vulnerable point, weak point, weakness