axletree
noun
ax·le·tree ˈak-səl-(ˌ)trē 
: axle sense 1b(1)
Word History
Etymology
Middle English axeltre, axiltre, borrowed from an Old Norse predecessor of Old Icelandic ǫxultré, from ǫxull "axle" (going back to Germanic *ahs-, base of *ahsō- "axle" + -ul-, perhaps a suffix of appurtenance) + tré "tree, mast, rafter, beam" — more at axis, tree entry 1
First Known Use
14th century, in the meaning defined above