gervi

Gear comes from Old Norse gervi (equipment, apparel, gear), from gørva (to make, to prepare). The word entered English through Norse contact during the Danelaw period (ninth to eleventh centuries). For centuries, 'gear' meant equipment, clothing, or personal belongings. A knight's gear was his armor. A sailor's gear was his kit. The word was about readiness — the stuff you needed to do your job.

The mechanical meaning — toothed wheels that mesh and transmit motion — appeared in the sixteenth century. The metaphor is apt: gears are the equipment that makes a machine ready to work. The first mechanical clocks used gear trains to translate the falling weight's energy into the measured movement of hands. The gears were the machine's equipment, its working parts. The Norse word for 'stuff you need' became the English word for 'parts that move.'

The automobile made 'gear' ubiquitous. First gear, second gear, reverse gear — the transmission's gear ratios determine how engine power reaches the wheels. 'Shifting gears' became a metaphor for changing pace or approach. 'In high gear' means working at maximum capacity. The machine word became a productivity metaphor within a generation of the automobile's mass adoption.

Modern English uses 'gear' in three overlapping senses: equipment (camping gear, fishing gear, climbing gear), mechanical components (gear wheels, gear ratios, gear trains), and preparation (gearing up for a project). All three trace back to the Norse gervi — the stuff you need, the state of being prepared, the readiness to work.