Words related to axle

axle-tree (n.)
also axletree, "bar or beam fitted crosswise under the body of a carriage and having wheels fitted to the ends," c. 1300, from axle (n.) + tree (n.).
axis (n.)

1540s, "imaginary motionless straight line around which a body (such as the Earth) rotates," from Latin axis "axle, pivot, axis of the earth or sky," from PIE *aks- "axis" (source also of Old English eax, Old High German ahsa "axle;" Greek axon "axis, axle, wagon;" Sanskrit aksah "an axle, axis, beam of a balance;" Lithuanian ašis "axle").

General sense of "straight line about which parts are arranged" is from 1660s. Figurative sense in world history of "alliance between Germany and Italy" (later extended unetymologically to include Japan) is from 1936. Original reference was to a "Rome-Berlin axis" in central Europe. The word later was used in reference to a London-Washington axis (World War II) and a Moscow-Peking axis (early Cold War).

aisle (n.)
late 14c., ele, "lateral division of a church" (usually separated from the nave or transept by a row of pillars), from Old French ele "wing (of a bird or an army), side of a ship" (12c., Modern French aile), from Latin ala, related to or contracted from axilla "wing, upper arm, armpit; wing of an army," from PIE *aks-la-, suffixed form of root *aks- "axis" (see axis). The notion is of "turning," which also connects it with axle.

Confused from 15c. with unrelated Middle English ile "island" (perhaps from notion of a "detached" part of a church), and so it took an unetymological -s- c. 1700 when isle did; by 1750 it had acquired an a-, on the model of French cognate aile. English aisle perhaps also was confused with alley, which helped give it the sense of "passage between rows of pews or seats" (1731), which subsequently was extended to railway cars, theaters, Congress, etc.
axillary (adj.)
"pertaining to the armpit or shoulder," 1610s, from Latin *axillaris, from axilla "armpit, upper arm, underpart of an upper wing" (see axle).