X-axis
From AoPSWiki
On a Cartesian plane, probably more well-known simply as a graph or coordinate plane, the X-axis is the horizontal line that is intersected by the Y-axis.
| Want to learn how to tackle those tough AMC/AIME/Olympiad counting and probability problems? Check out Art of Problem Solving's Intermediate Counting & Probability by David Patrick. |
On a Cartesian plane, probably more well-known simply as a graph or coordinate plane, the X-axis is the horizontal line that is intersected by the Y-axis.

