1 [countable/uncountable] the part of an engine that changes engine power into movement. Most cars in the UK have 5 or 6 gears that you operate yourself
change gear: Helen changed gear as she approached the junction.
first/second etc gear: At forty miles an hour you should be in fourth gear.
low/high gear: Always use a low gear when driving down a steep hill.
grind/crash the gears (=make a noise when changing gear because you do not do it correctly): You’ll ruin the gearbox if you keep grinding the gears like that.
in gear (=with one of the gears connected so that the power of the engine will make the wheels move): The car won’t move unless you’re in gear.
out of gear (=with no gears connected): Take the car out of gear.
Synonyms and related words