unfasten unfast • unfastenable · · · Info · Definitions · Antonyms · Characters · · unfasten · · Text Latin · · Script 8 · · Length Definitions · · · (verb) cause to become undone. Example: "Unfasten your belt." · · Verb Definition 1 (verb) become undone or untied. Example: "The shoelaces unfastened." · · Verb Definition 2 Antonyms · · · fasten · · Antonym 0 fix · · Antonym 1 secure · · Antonym 2 Characters · · a latin small letter a U+0061 e latin small letter e U+0065 f latin small letter f U+0066 n latin small letter n U+006E s latin small letter s U+0073 t latin small letter t U+0074 u latin small letter u U+0075