landing gear

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The components of an aircraft or a spacecraft that support the weight of the craft and its load and give it mobility on ground or water.

from the GNU version of the Collaborative International Dictionary of English.

• noun The wheels and attached structures under an airplane that support it and allow it to move when on the ground; also, the floats or pontoons of an amphibious airplane together with their supporting structures. Landing gear may be fixed rigidly in place, or retractable when in flight.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun the wheels, tyres, brakes, shock absorbers etc of an aircraft; its undercarriage

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an undercarriage that supports the weight of the plane when it is on the ground