Definition of axis noun from the Oxford Advanced American Dictionary

axis

noun
/ˈæksəs/
 
plural axes
/ˈæksiz/
 
 
1 an imaginary line through the center of an object, around which the object turnsMars takes longer to revolve on its axis than the earth does.2 (technical) a fixed line against which the positions of points are measured, especially points on a graphthe vertical/horizontal axisThe real cost is measured along the horizontal axis and the quantity of labor is measured along the vertical axis.The main road is on a north-south axis.3 (geometry) a line that divides a shape into two equal partsan axis of symmetryThe axis of a circle is its diameter.4 [usually singular] (formal) an agreement or alliance between two or more countriesthe Axis Powers of World War II