axial line

from The Collaborative International Dictionary of English v.0.48

Axial \Ax"i*al\, a.
   1. Of or pertaining to an axis; of the nature of, or
      resembling, an axis; around an axis.
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            To take on an axial, and not an equatorial,
            direction.                            --Nichol.
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   2. (Anat.) Belonging to the axis of the body; as, the axial
      skeleton; or to the axis of any appendage or organ; as,
      the axial bones.
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   {Axial line} (Magnetism), the line taken by the magnetic
      force in passing from one pole of a horseshoe magnet to
      the other. --Faraday.
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