freewheel
noun
Definitions
A device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft.
verb
Definitions
(of a gear) To continue spinning after disengagement.
(of a cyclist) To ride a bicycle without pedalling, e.g. downhill.
(of a motorist) To operate a motor vehicle which is coasting without power, e.g. downhill.
(by extension) To operate free from constraints.