← BackshareGuessunfastened/ʌnˈfæsənd/adjectiveNot closed, tied, or attached; loose.Her shoelaces were unfastened, so she tripped.The unfastened gate swung open in the wind.He noticed his backpack was unfastened and his books were falling out.SynonymslooseopendetachedAntonymsfastenedsecure