| XDS | eXternal Data Source |
| XMI | XML Metadata Interchange |
| XML | eXtensible Markup Language |
| XWD | X-Window screen dump |
| Y2K | Year 2000 (problem) |
| ZCTA | ZipCode Tabulation Area |
| ZGI | Zentrales Geologisches Institut (German Democratic Republic) |
| ZGS | Zambia Geological Survey Dept. |
| ZIMAS | Zoning Information and Map Access System (Los Angeles, Calif.) |
| ZLI | Zia Landform Images |
| ZMA | Zone Map Automation (Los Angeles, Calif.) |
| ZPS | ZEH plotting software |
| ZRC | Znanstvenoraziskovalni Center (Slovenske Akademije Znanosti in Umetnosti) |
| ZS | Zambia Survey Dept. |
| ZTS | Zoom Transfer Scope |