landing gear

Short definition from Wiktionary

Noun

1. 1
   The wheels, tyres, brakes, shock absorbers etc of an aircraft; its undercarriage.
2. 2
   Any of the assemblies which support an aircraft when it is on the ground.
3. 3
   The bipod stand found near the front end underneath a truck trailer, used to keep the trailer level when not attached to a tractor truck.