| Xerxes | Kserkses I |
| Xerxes I of Persia | Kserkses |
| Xerxes II of Persia | Kserkses II |
| Xfce | Xfce |
| XGA | EXtended Graphics Array |
| Xgl | XGL |
| Xhosa | xhosa |
| Xhosa language | Język xhosa |
| Xhosa Wars | Wojny Xhosa |
| XHTML | XHTML |
| xi | ksi |
| Xi Puppis | Azmidiske |
| Xia | Dynastia Xia |
| Xia Dynasty | Dynastia Xia |
| Xiamen | Xiamen |
| Xiangkhoang Province | Prowincja Xieng Khouang |
| Xianyang | Xianyang |
| Xiaolin Showdown | Xiaolin - pojedynek mistrzów |
| Xichang Satellite Launch Center | Kosmodrom Xichang |
| Xie Jun | Xie Jun |
| Xiehouyu | Przysłowia chińskie |
| Xindi | Xindi |
| Xingu | Xingu |
| Xingu River | Xingu |
| Xinhua News Agency | Xinhua |
| Xining | Xining |
| Xinjiang | Sinkiang |
| Xinjiangovenator | Ksinjangowenator |
| Xiong Ni | Xiong Ni |
| Xiongnu | Xiongnu |
| Xipe Totec | Xipe Totec |
| xiphoid process | wyrostek mieczykowaty |
| Xiphos | Xiphos |
| Xiuhtecuhtli | Xiuhtecuhtli |
| XL Airways | XL Airways |
| Xmas | Boże Narodzenie |
| XML | XML |
| XML editor | Edytor XML |
| XML Namespace | Namespaces in XML |
| XML Schema | XML Schema |
| XML Schema Definition | XML Schema |
| XMLHttpRequest | XMLHTTP |
| XMM-Newton | XMM-Newton |
| XMMS | XMMS |
| XMODEM | XMODEM |
| XMPP | Jabber |
| XNOR gate | XNOR |
| Xochimilco | Xochimilco |
| Xochipilli | Xochipilli |
| Xochiquetzal | Xochiquetzal |
| Xolotl | Xolotl |
| XOOPS | XOOPS |
| XOOPS Cube | XOOPS |
| xor | albo |
| XOR swap algorithm | Zamiana wartości zmiennych |
| Xorazm Province | Chorezm |
| XP | Punkt doświadczenia |
| XPCOM | XPCOM |
| XPInstall | XPI |
| XQuery | XQuery |
| XScale | Intel XScale |
| XSL Formatting Objects | XSL Formatting Objects |
| XSL Transformations | XSL Transformations |
| XTree | XTree |
| Xtro | Xtro |
| Xu Yuhua | Xu Yuhua |
| Xuanhanosaurus | Ksuananozaur |
| Xuanhuaceratops | Ksuanhuaceratops |
| XUL | XUL |
| Xun Zi | Xunzi |
| Xuzhou | Xuzhou |
| Xvid | Xvid |
| XxxHolic | ×××HOLiC |
| xylem | drewno |
| xylene | ksylen |
| xylo- | ksylo- |
| xylography | drzeworytnictwo |
| xylophage | ksylofag |
| Xylophagy | Ksylofagia |
| xylophone | ksylofon |
| xylophonist | ksylofonista |
| xylose | ksyloza |
