| Acronym | Definition |
|---|
| WSI | Water Safety Instructor |
| WSI | Wall Street Institute |
| WSI | Water Systems, Inc. (various locations) |
| WSI | Window Set Interval |
| WSI | Web Server Integration |
| WSI | Wireless Strategic Initiative |
| WSI | Wirtschafts- und Sozialwissenschaftliches Institut (German: Institute for Economic and Social Science; Germany) |
| WSI | Wilhelm Schickard Institut (German institute) |
| WSI | Wackenhut Services Inc. (Palm Beach Gardens, FL) |
| WSI | Wafer Scale Integration |
| WSI | Web Services Interoperability |
| WSI | Web Services Interface (software) |
| WSI | World Security Institute (Washington, DC) |
| WSI | World Sindhi Institute (Pakistan) |
| WSI | Weather Services International Corporation |
| WSI | Workplace Skills Initiative (Industry Canada) |
| WSI | Welfare State International |
| WSI | Whole Sky Image (meteorology) |
| WSI | Workforce Safety Insurance (North Dakota) |
| WSI | Web Services Initiative (various organizations) |
| WSI | Written Scheme of Investigation (document prepared as part of archaeological fieldwork) |
| WSI | Wachovia Securities, Inc. (banking) |
| WSI | Weapon System Integration |
| WSI | Whole School Initiative (various locations) |
| WSI | Web Services Internationalization |
| WSI | Wireless Systems International |
| WSI | Web Services Intermediary |
| WSI | Whole Schools Institute |
| WSI | Water Soluble Index |
| WSI | Warfare Studies Institute |
| WSI | Wordtext Systems Incorporated |
| WSI | Wellstart International |
| WSI | Weapons System Information Manual |
| WSI | Waste-Spark Ignition |
| WSI | Woman Sergeant Instructor |
| WSI | War Service Increment (UK) |