axle

noun
  1. A rod or spindle (either fixed or rotating) passing through the center of a wheel or group of wheels. noun
    The car's axle was damaged in the accident, making it difficult to drive.
    The mechanic inspected the axle to ensure it was properly aligned.
  2. The central shaft for a rotating wheel or gear, which can be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. noun
    The bicycle's axle needed lubrication to reduce friction.
    The engineer designed a new type of axle to improve vehicle performance.