ax·le \ˈaksəl\noun (-s) Etymology: Middle English axel- (as in axeltre axletree) — more at axletree 1.archaic: axis < the axle of the earth > 2. a.: the pin, bar, or shaft on which or with which a wheel or pair of wheels revolves — see dead axle, floating axle, live axle b. (1): the spindle of an axletree (2): axletree