axis >> /ˈæksəs/
Definition: [noun] An imaginary line about which a body rotates.
Example: the Earth revolves on its axis once every 24 hours
Definition: [noun] A fixed reference line for the measurement of coordinates.
Example: the variable that is thought of as a cause is placed on the horizontal axis, and the variable that is thought of as an effect on the vertical axis
Definition: [noun] A straight central part in a structure to which other parts are connected.
Example: A shaft parallel to the transmission-engine axis connects the transfer casing to the angle drive powering the front wheels.
Definition: [noun] The second cervical vertebra, below the atlas at the top of the backbone.
Example: The muscle's origin may not ascend above the axis or descend below the third thoracic vertebra.
Definition: [noun] An agreement or alliance between two or more countries that forms a center for an eventual larger grouping of nations.
Example: the Anglo-American axis