| X-SAR | X-Band Synthetic Aperture Radar | - | Computer Acronyms(common) |
| XAES | X-ray Excited Auger Electron Spectroscopy | - | Computer Acronyms(common) |
| XAFS | X-ray Absorption Fine Structure | - | Computer Acronyms(common) |
| XANES | X-ray Absorption Near Edge Structure | - | Computer Acronyms(common) |
| XAPS | X-ray Appearance Potential Spectroscopy | - | Computer Acronyms(common) |
| XAS | X-ray Absorption Spectroscopy | - | Computer Acronyms(common) |
| XBIS | X-ray Bremsstrahlung Isochromat Spectroscopy | - | Computer Acronyms(common) |
| XC | Exchange-coulomb Potential | - | Computer Acronyms(common) |
| XCC | Expectation-value Coupled-cluster (in Correlation Energies And Electronic Properties Of Many-electron Systems Calcns.) | - | Computer Acronyms(common) |
| XD | Exothermic Dispersion | - | Computer Acronyms(common) |
| XDBP | Halogenated Disinfection By-product | - | Computer Acronyms(common) |
| XEAES | X-ray Excited Auger Electron Spectroscopy | - | Computer Acronyms(common) |
| XEAPS | X-ray Excited Electron Appearance Potential Spectroscopy | - | Computer Acronyms(common) |
| XEDS | X-ray Energy Dispersive Spectroscopy | - | Computer Acronyms(common) |
| XEOL | X-ray Excited Optical Luminescence | - | Computer Acronyms(common) |
| XES | X-ray Emission Spectroscopy | - | Computer Acronyms(common) |
| XFA | X-ray Fluorescence Analysis | - | Computer Acronyms(common) |
| XFH | X-ray Fluorescence Holography | - | Computer Acronyms(common) |
| XGRS | X-ray/gamma-ray Spectrometer | - | Computer Acronyms(common) |
| XHDPE | Cross-linked | - | Computer Acronyms(common) |
| XHV | Extremely High Vacuum | - | Computer Acronyms(common) |
| XIAES | X-ray Induced Auger Emission Spectroscopy | - | Computer Acronyms(common) |
| XIS | X-ray Isochromat Spectroscopy | - | Computer Acronyms(common) |
| XLPE | Crosslinked Polyethylene | - | Computer Acronyms(common) |
| XMA | X-ray Microanalysis | - | Computer Acronyms(common) |
| XMCD | X-ray Magnetic Circular Dichroism | - | Computer Acronyms(common) |
| XMLD | X-ray Magnetic Linear Dichroism | - | Computer Acronyms(common) |
| XMM | X-ray Multi-Mirror | - | Computer Acronyms(common) |
| XMP | Xanthosine 5'-phosphate | - | Computer Acronyms(common) |
| XMPA | X-ray Electron Microprobe Analysis | - | Computer Acronyms(common) |
| XNBR | Carboxylated Nitrile Rubber | - | Computer Acronyms(common) |
| XPD | X-ray Photoelectron Diffraction | - | Computer Acronyms(common) |
| XPED | X-ray Photoelectron Diffractometry | - | Computer Acronyms(common) |
| XPEEM | X-ray Photoemission Electron Microscopy | - | Computer Acronyms(common) |
| XPES | X-ray Photoelectron Spectroscopy | - | Computer Acronyms(common) |
| XPM | Cross-phase Modulation | - | Computer Acronyms(common) |
| XPM | X-ray Photoelectron Microscopy | - | Computer Acronyms(common) |
| XPS | X-ray Photoelectron Spectroscopy | - | Computer Acronyms(common) |
| XRCF | X-ray Calibration Facility | - | Computer Acronyms(common) |
| XRD | X-ray Diffraction Analysis | - | Computer Acronyms(common) |
| XRES | X-ray Emission Spectroscopy | - | Computer Acronyms(common) |
| XRF | X-ray Fluorescence | - | Computer Acronyms(common) |
| XRFA | X-ray Fluorescence Analysis | - | Computer Acronyms(common) |
| XRFS | X-ray Fluorescence Spectroscopy | - | Computer Acronyms(common) |
| XRMA | X-ray Microanalysis | - | Computer Acronyms(common) |
| XRMF | X-ray Microfluorescence | - | Computer Acronyms(common) |
| XRPD | X-ray Powder Diffraction | - | Computer Acronyms(common) |
| XRR | X-ray Reflectometry | - | Computer Acronyms(common) |
| XRS | X-Ray Spectroscopy | - | Computer Acronyms(common) |
| XSAD | X-ray Small Angle Diffraction | - | Computer Acronyms(common) |
| XSW | X-ray Standing Wave | - | Computer Acronyms(common) |
| XTEM | Cross-sectional Transmission Electron Microscopy | - | Computer Acronyms(common) |
| XTM | X-ray Tomographic Microscopy | - | Computer Acronyms(common) |
| XUV | Extreme Ultraviolet | - | Computer Acronyms(common) |
