verb (used with object) 1.to open (a door, window, etc.) by or as if by removing a bolt; unlock; unfasten.
2.to release, as by the removal of threaded bolts: He unscrewed the nuts and unbolted the inspection cover.
verb (used without object) 3.to become unbolted or unfastened.
Origin: 1425–75; late Middle English; see
un-2 +
bolt1