SDI

• SDI (arcade game), 1987, by Sega
• S.D.I. (video game), 1986, by Cinemaware

• Samsung SDI, battery manufacturer
• Scottish Development International
• Scuba Diving International
• SDI Media Group, providing subtitling and language services
• SDI Presence, US IT consultancy
• SDI Technologies, a consumer electronics manufacturer, New Jersey, U.S.A.
• Service Desk Institute, for computer help desk staff
• Slum Dwellers International
• {{lang|it|Socialisti Democratici Italiani}} (Italian Democratic Socialists), a political party
• Software Design Inc.
• Spiritual Directors International, supporting spiritual direction
• Steel Dynamics, Inc., a steel producer, Indiana, US.A.

• Serial data input in the Serial Peripheral Interface bus
• Serial digital interface for sending video signals over coaxial cable
• Single document interface, a style of graphical user interface
• Software-defined infrastructure, with no human intervention
• Spatial data infrastructure
• Standard Disk Interconnect, a DEC standard
• Statistical Design Institute's SDI Tools for Microsoft Excel
• System Deployment Image, a Microsoft disk image file format

• Sulfadimidine, an antibiotic

• Selective dissemination of information
• Silt density index in reverse osmosis systems
• Smoke-developed index, the concentration of smoke emitted by a material
• Spiral Dynamics Integral, a model of evolutionary development
• Stand density index, of the stocking of a stand of trees
• Subsurface drip irrigation
• Suction Diesel Injection, a Volkswagen diesel engine

• Saidor Airport (IATA code), in Madang Province, Papua New Guinea
• Socio-Demographic Index of the Global Burden of Disease Study
• State Disability Insurance of California, US
• Strategic Defense Initiative, US anti-missile project

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