← BackshareGuessunfastening/ʌnˈfæsənɪŋ/nounThe act of opening or releasing something that is closed or attached.The unfastening of the lock required a special key.The unfastening of the seatbelt took only a second.She practiced the unfastening of the knot until it became easy.SynonymsreleaseopeningAntonymsfastening