2 Answers

ax·is1    [ak-sis] Show IPA
noun, plural ax·es  [ak-seez] Show IPA.
1.
the line about which a rotating body, such as the earth, turns.
2.
Mathematics .
a.
a central line that bisects a two-dimensional body or figure.
b.
a line about which a three-dimensional body or figure is symmetrical.
3.
Anatomy .
a.
a central or principal structure, about which something turns or is arranged: the skeletal axis.
b.
the second cervical vertebra.
4.
Botany . the longitudinal support on which organs or parts are arranged; the stem and root; the central line of any body.
5.
Analytic Geometry . any line used as a fixed reference in conjunction with one or more other references for determining the position of a point or of a series of points forming a curve or a surface. Compare x-axis, y-axis.

http://dictionary.reference.com/browse/axis

Two Axis,