| X | Inductive Reactance |
| XANES | X-ray Adsorption Near Edge Structure Spectroscopy |
| XAS | X-ray Absorption Spctrosopcy |
| Xe | Xenon |
| XLL | Exit Loadlock |
| XLS | Excimer Laser System |
| XLS | Extended Light Scatterer |
| XPS | X-ray Photoelectron Spectroscopy |
| XRD | X-ray Diffraction |
| XRF | X-ray Fluorescence Spectrometry |
| XRR | X-ray Reflectometry |
| XSEM | Cross-sectional Scanning Electron Microscopy |