. 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. |

| y-ax·is (wī'āk'sĭs) n. pl. y-ax·es (wī'āk'sēz)
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y-axis (wī'āk'sĭs) Pronunciation Key
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