1) Around a central line 2) How the Earth moves 3) With respect to a graph line 4) With respect to an axis 
• (adv.) In relation to, or in a line with, an axis; in the axial (magnetic) line.
<anatomy> In relation to, or in a line with, an axis; in the axial line. ... (12 Mar 1998) ... 
Ax'i·al·ly adverb In relation to, or in a line with, an axis; in the axial (magnetic) line. 
[adv] - with respect to an axis
adverb with respect to an axis; `the jet was directed axially toward the cathode`