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