| X-ray | named it X-radiation to signify an unknown type of radiation (X represents the “unknown” in math) |
| x64 | 64-bit version of the x86 instruction set |
| x86 | generic name for Intel processors released after the original 8086 processor |
| xACT | X Audio Compression Toolkit |
| XAML | eXtensible Application Markup Language |
| XAMPP | X (cross plaftorm), Apache, MySQL, PHP, Perl |
| XAT | Xavier Aptitude Test |
| XBL | XML Binding Language |
| Xbox | shortened from DirectX box |
| XBRL | eXtensible Business Reporting Language |
| xDSL | X (any type of) Digital Subscriber Line |
| Xerox | from the term Xerography means “dry writing” |
| XGA | Extended Graphics Array |
| XHR | XMLHttpRequest |
| XHTML | EXtensible HyperText Markup Language |
| Xiaomi | Xiao + Mi |
| XIMB | Xavier Institute of Management, Bhubaneswar |
| XIME | Xavier Institute of Management and Entrepreneurship |
| XIRR | eXtended Internal Rate of Return |
| xkcd | not an abbreviation, just a word with no phonetic pronunciation |
| XL | Extra Large |
| XL | Excess of Loss |
| XLIX | Roman numerals for 49 |
| XLP | Crosslinked Polyethylene |
| XLP | X-Linked Lymphoproliferative |
| XLP | EXtreme Low-Power |
| XLPE | Cross Linked Polyethylene |
| XLRI | Xavier School of Management |
| XLRI | X-Linked Recessive Ichthyosis |
| XLS | Microsoft Excel Spreadsheet |
| XLS | Saint-Louis Airport |
| XML | eXtensible Markup Language |
| XMS | Extended Memory Specification |
| XNS | Xerox Network Systems |
| xoxo | Hugs and Kisses |
| XP | EXPerience |
| XP | Extreme Programming |
| XP | Xeroderma Pigmentosum |
| XSLT | XML(Extensible Markup Language) Stylesheet Language Transformations |
| XTML | Extensible Telephony Markup Language |
| XUV | Extreme Ultraviolet |
| XUV | Crossover Utility Vehicle |
| xvda | Xen Virtual Disk A (aka xvd*) |
| XviD | backwards for DivX |
| XXL | Double Extra Large |
| XXX | Roman numeral for thirty (30) |
| XXX | Adult film rating |
| XXX | a mark of beer strength |
| XXX | No currency transactions |
| xxx | Top level domain specifically for the adult entertainment industry |
| XXXL | Trible Extra Large |
