UNFASTEN
unfasten
(verb) become undone or untied; “The shoelaces unfastened”
unfasten
(verb) cause to become undone; “unfasten your belt”
Source: WordNet® 3.1
Etymology
Verb
unfasten (third-person singular simple present unfastens, present participle unfastening, simple past and past participle unfastened)
(transitive) To detach from any connecting agency or link; to disconnect.
(intransitive) To come unloosed or untied.
Synonyms
• undo
Antonyms
• do up
• button
• button up
• tie up
• zip
• zip up
Hyponyms
• unbutton
• untie
• unzip
Source: Wiktionary
Un*fas"ten, v. t. Etym: [1st pref. un- + fasten.]
Definition: To loose; to unfix; to unbind; to untie.
Source: Webster’s Unabridged Dictionary 1913 Edition