| | Acronyms | Meaning / Significance | Source |
| X-Series | CCITT data
communication network | | | X-TELL | cross tell | | | XI | exercise
indicator | | | XID | exchange
identification | | | XMIT | transmit | | | XMITR | transmitter | | | XML | eXtensible Markup Language | World Wide
Web Consortium (W3C) | | XML | exercise manning
list | | | XMSN | transmission | | | XMT | exempt | | | XOR | logical operator | | | XSERV | aircraft x-servicing ample gain programme subsystem | | | XTAL | crystal | |
|