"pertaining to the armpit or shoulder," 1610s, from Latin *axillaris, from axilla "armpit, upper arm, underpart of an upper wing" (see axle).
Entries linking to axillary
axle n.
"pole or pin upon which a wheel revolves" (properly, the round ends of the axle-tree which are inserted in the hubs or naves of the wheels), 1630s, from Middle English axel-, from some combination of Old English eax and Old Norse öxull "axis," both from Proto-Germanic *akhsulaz (source also of Old English eaxl "shoulder," oxta, ohsta "armpit," which survived as dialectal oxter; also Old Saxon ahsla, Old High German ahsala, German Achsel "shoulder"), from PIE *aks- "axis" (see axis, which is from the Latin cognate of this Germanic word). Before 14c. it was found only in the compound axle-tree.