| Acronym | Definition |
|---|
| HSI | Humane Society International |
| HSI | Hang Seng Index |
| HSI | Homeland Security Investigations (US Immigration and Customs Enforcement) |
| HSI | High Speed Internet |
| HSI | Hispanic Serving Institutions |
| HSI | Health Sciences Institute (Baltimore, MD, USA) |
| HSI | Horizon Software International (Duluth, GA) |
| HSI | Horizontal Situation Indicator (aviation) |
| HSI | Health Systems International (various locations) |
| HSI | Human Systems Integration |
| HSI | Homeland Security Intelligence (various organizations) |
| HSI | H323 Signaling Interface |
| HSI | H323 Service Interface |
| HSI | Handmade Software Inc. |
| HSI | High Speed Interconnect |
| HSI | Hierarchical Storage Interface |
| HSI | High Speed Serial Interface |
| HSI | Hyperspectral Imagery |
| HSI | Hue Saturation Intensity (color model) |
| HSI | Human System Integration |
| HSI | Human Swine Influenza |
| HSI | High Speed Interface |
| HSI | High School Institute (various locations) |
| HSI | Hospitality Solutions International |
| HSI | Hyperspectral Imager |
| HSI | Hot Section Inspection |
| HSI | Hot Surface Igniter |
| HSI | Home Study International |
| HSI | Heat Stress Index |
| HSI | Hardware-Software Integration |
| HSI | Health Services Inspection (formerly HSMI) |
| HSI | Home School, Inc. |
| HSI | Hastings, NE, USA (Airport Code) |
| HSI | Human Synergistics International (Plymouth, MI) |
| HSI | Human Systems Interface |
| HSI | Health Services International |
| HSI | High Speed Infrared (Film, Kodak) |
| HSI | Hungarian Standards Institution |
| HSI | Health Sciences Initiative (San Diego Science Alliance; California) |
| HSI | Hudson Smith International |
| HSI | Handling Speed Intelligently (running training club founded by coach John Smith; Los Angeles, CA) |
| HSI | Home Safety Inspection (Australia) |
| HSI | Horsepower per Square Inch (physics) |
| HSI | Hellenic Society of Immunology |
| HSI | Health Sustainability Initiative (Canada) |
| HSI | Home Station Instrumentation (Army) |
| HSI | Horizon Situation Indicator |
| HSI | High-Speed Interferometer |
| HSI | Hours Since Inspection |
| HSI | Handbook of Service Instruction |
| HSI | Host-Specific Interface |
| HSI | Habitat Stability Index |
| HSI | Harsh Squirrel Interaction (training team) |
| HSI | Heading Select Indicator |