ax·le·tree \ˈaksəl.ˌtrē, -ltri\noun (-s) Etymology: Middle English axeltre, from Old Norse öxultrē, from öxull axle + trē beam, tree — more at axis, tree 1.: a fixed bar or beam having bearings at its ends upon which the wheels (as of a carriage, cart, or wagon) revolve 2.obsolete: axis