- x-Axis ({{MathWorld | urlname=x-Axis | title=x-Axis}}): x-Axis
- Xiangqi ({{MathWorld | urlname=Xiangqi | title=Xiangqi}}): Xiangqi
- Xi-Function ({{MathWorld | urlname=Xi-Function | title=Xi-Function}}): Xi-Function
- x-Intercept ({{MathWorld | urlname=x-Intercept | title=x-Intercept}}): x-Intercept
- XNOR ({{MathWorld | urlname=XNOR | title=XNOR}}): XNOR
- Xor ({{MathWorld | urlname=Xor | title=Xor}}): Xor
- XOR ({{MathWorld | urlname=XOR | title=XOR}}): XOR