Pronunciation: (eks'ak"sis), [key]
—pl. x-ax•esPronunciation: (eks'ak"sēz). [key] Math.
1. Also called axis of abscissas. (in a plane Cartesian coordinate system) the axis, usually horizontal, along which the abscissa is measured and from which the ordinate is measured. See diag. under abscissa.
2. (in a three-dimensional Cartesian coordinate system) the axis along which values of x are measured and at which both y and z equal zero.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.