Axle/ˈæksl/ Definition 1 of 4Pro Tip 1/2Vehicle Connection An axle is crucial for a vehicle's wheels to function together smoothly. The mechanic fixed the bent axle that caused the wheels to wobble. Pro Tip 2/2Mechanical Term Axle is often used in automotive contexts, familiar to mechanics and car enthusiasts. Upgrading the front axle can improve a car's handling.