The Collaborative International Dictionary of English v.0.48:

Axle \Ax"le\ ([a^]ks"'l), n. [OE. axel, exel, shoulder, AS.
   eaxl; akin to AS. eax axle, Sw. & Dan. axel shoulder, axle,
   G. achse axle, achsel shoulder, L. axis axle, Gr. 'a`xwn,
   Skr. aksha, L. axilla shoulder joint: cf. F. essieu, axle,
   OF. aissel, fr. dim. of L. axis. [root]205. Cf. 2d Axis.]
   1. The pin or spindle on which a wheel revolves, or which
      revolves with a wheel.
      [1913 Webster]

   2. A transverse bar or shaft connecting the opposite wheels
      of a car or carriage; an axletree.
      [1913 Webster]

   3. An axis; as, the sun's axle.
      [1913 Webster]

            Had from her axle torn
            The steadfast earth.                  --Milton.
      [1913 Webster]

   Note: Railway axles are called leading and trailing from
         their position in the front or in the rear of a car or
         truck respectively.
         [1913 Webster]

WordNet (r) 3.0 (2006):

axle
    n 1: a shaft on which a wheel rotates

The Free On-line Dictionary of Computing (30 December 2018):

AXLE

    An early string processing language in which a
   program consists of an "assertion table" specifying patterns
   and an "imperative table" specifying replacements.

   ["AXLE: An Axiomatic Language for String Transformations",
   K. Cohen et al, CACM 8(11):657-661, Nov 1965].

   (2009-02-10)