Definition of "unfasten" []

• To separate the connected parts of. (verb-transitive)
• To become loosened or separated. (verb-intransitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "One of the Indians stepped up and proceeded to unfasten his pack-straps."
• "He let her go long enough to unfasten his necklace."
• "All those little frog fastenings—he itched to unfasten them one by one."