| Acronym | Definition |
|---|
| SDI | Strategic Defense Initiative (US DoD) |
| SDI | Serial Digital Interface |
| SDI | State Disability Insurance |
| SDI | Spatial Data Infrastructure |
| SDI | Strength Deployment Inventory (Relationship Awareness Theory) |
| SDI | Spiritual Directors International |
| SDI | Single Document Interface (Microsoft) |
| SDI | Silt Density Index |
| SDI | Strategic Diagnostics Inc. (Newark, DE) |
| SDI | Steel Door Institute (Cleveland, Ohio) |
| SDI | Scottish Development International (Glasgow, Scotland) |
| SDI | Stand Density Index |
| SDI | Scuba Diving International |
| SDI | Selective Dissemination of Information |
| SDI | Socialisti Democratici Italiani (Italian Social Democrats) |
| SDI | Socialisti Democratici Italiani (Italian Democratic Socialist party) |
| SDI | Sustainable Development Indicators |
| SDI | Steel Deck Institute |
| SDI | Spatial Development Initiative (South African private sector development & jobs programs) |
| SDI | Southern Dental Industries |
| SDI | Storage Device Interface |
| SDI | Spiral Dynamics Integral |
| SDI | Senior Drill Instructor |
| SDI | Sonic Drive In (restaurant) |
| SDI | Shack/Slum Dwellers International |
| SDI | Serial Data In |
| SDI | Strategic Distribution, Inc. |
| SDI | Systems Design Inc (Sparks, NV) |
| SDI | Sarawak Development Institute |
| SDI | Standard Data Interface |
| SDI | Système de Détection Incendie (French: Fire Detection System) |
| SDI | Subsidy Dependence Index (finance) |
| SDI | System Development Inc. |
| SDI | Syndicat des Indépendants |
| SDI | Statistics on Depository Institutions (FDIC) |
| SDI | Source Destination Identifier (avionics) |
| SDI | Science Data Interface |
| SDI | Special Duty Identifier |
| SDI | Sustainable Development Innovation |
| SDI | Stamp Dealers International |
| SDI | Soil Dryness Index |
| SDI | Sage Database Inquiry |
| SDI | Steel Dynamics, Incorporated |
| SDI | Saugdiesel Direct Injection (engine) |
| SDI | Switched Digital International |
| SDI | Systemically Dangerous Institution (economics) |
| SDI | Secure Dial-in |
| SDI | Standard Disbursing Initiative (US DoD) |
| SDI | Suction Diesel Injection |
| SDI | Supplier Development Initiative (Canada) |
| SDI | Stress Day Index |
| SDI | Standard Diesel Injection |
| SDI | Superior Deicers Inc. (manufacturers of aviation ground support equipment) |
| SDI | Service Delivery Index (also seen as SDIX) |
| SDI | Soft Decision Information |
| SDI | Spatial Domain Interferometry |
| SDI | Ships Drawing Index |
| SDI | Safety Data Initiative |
| SDI | Software Digest Incorporated |
| SDI | Spectroscopic Diagnostics, Inc (Torrance CA) |
| SDI | Survey Detection and Identification |
| SDI | Stork Digital Imaging BV (Netherlands) |
| SDI | Subtitling & Dubbing International |
| SDI | Simulation Data Interface |
| SDI | Sistemas Detectores de Intrusão |
| SDI | Sales-Diffusion Index |
| SDI | Same Direction Interference |
| SDI | Selective Description Item |
| SDI | Smart Database Interface |
| SDI | Self-Descriptive Inventory (psychology) |
| SDI | Solution Datacom Incorporated |
| SDI | Standard Disk Interface/Interconnect |
| SDI | Special Delivery Instruction |
| SDI | Sudden Death in Infancy |
| SDI | Scanned Document Image |
| SDI | Subjective Disposable Income |
| SDI | Ship Data Index |
| SDI | Shaped Dielectric Insert |
| SDI | Sales Distribution Information |
| SDI | System Design and Integration Pty. Ltd. (Australia) |
| SDI | Standard Deviation Index (data analysis) |
| SDI | Supplier Diversity Initiative |
| SDI | Securities Disclosure of Interests (ordinance; Honk Kong) |
| SDI | Single Damascene Interconnect (semiconduction technology) |