English definition of “gear”
› the parts in a car or bicycle that control how fast the wheels turn: I have a mountain bike with 21 gears. I changed gear.
first, second, third, etc. gear › a particular position of the gears in a car, bicycle, etc. that controls how fast the wheels turn: I left the car in first gear.
› [no plural] the clothes and things that you use for a particular purpose: sports gear