(algebraic geometry) The axis on a graph that is usually drawn from bottom to top and usually shows the range of values of variable dependent on one other variable, or the second of two independent variables.

Self-evident or unquestionable. [from 18th c.] / (mathematics) Relating to or containing axioms. [from 19th c.]

Relating to, resembling, or situated on an axis / (anatomy) Belonging to the axis of the body, or to the axis of any appendage or organ / (botany) In the same direction as the axis, parallel to the axis.

(ornithology) A flight feather that appears between the primaries and secondaries on some birds. / (dentistry) A plane parallel to the surface of a tooth.

A critically endangered salamander found in the elevated lakes of Mexico, Ambystoma mexicanum.

(philosophy) A seemingly self-evident or necessary truth which is based on assumption; a principle or proposition which cannot actually be proved or disproved.

(obsolete) Shoulder.

The pin or spindle on which a wheel revolves, or which revolves with a wheel. / A transverse bar or shaft connecting the opposite wheels of a car or carriage; an axletree.

(cytology) A nerve fibre which is a long slender projection of a nerve cell, and which conducts nerve impulses away from the body of the cell to a synapse.

A group of states accused by George W. Bush of sponsoring terrorism and seeking weapons of mass destruction, originally defined as Iran, Iraq, and North Korea.