the world > relative properties > wholeness > mutual relation of parts to whole > separation > separation or detachment > loosening or unfastening > loosen, unfasten, or untie [verb (transitive)] > and release > by specific means (5)
To detach, remove, release, extract, by untwisting. Also figurative.
To loosen, detach, or set free, by untwining. Also figurative.
transitive. To reverse or undo the action of knocking (something).
transitive. To unfasten by removing a pin, wedge, bolt, etc. Cf. key, v. 2a. Now rare.
(un-, prefix2 affix 1a affix 1.)