Definition from Wiktionary, the free dictionary
freewheel (plural freewheels)
- a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft.
- (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.