x-axis
noun [ S ] mathematics specialized uk/ˈeksˌæk.sɪs/ us/ˈeksˌæk.sɪs/
X轴，横轴（沿图表或地图的底部从左到右排列的一组数字或座标）
the line of figures or coordinates that are arranged from left to right along the bottom of a graph or map
Synonym: horizontal axis