Definition of "unfasten"

unfasten

verb
third-person singular simple present unfastens, present participle unfastening, simple past and past participle unfastened
1. (transitive) To detach from any connecting agency or link; to disconnect.
  Quotations
  He doth unfasten so and shake a friend.
  c. 1596–1599 (date written), William Shakespeare, “The Second Part of Henry the Fourth, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act IV, scene i]
2. (intransitive) To come unloosed or untied.