y-axis

noun, plural y-ax·es [wahy-ak-seez] /ˈwaɪˌæk siz/. Mathematics.

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.
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.

noun

1. a reference axis, usually vertical, of a graph or two- or three-dimensional Cartesian coordinate system along which the y- coordinate is measured

1. The vertical axis of a two-dimensional Cartesian coordinate system.
2. One of the three axes of a three-dimensional Cartesian coordinate system.