SSI

SSI may refer to:

Companies

 * Sahaviriya Steel Industries, Thai steel company
 * Samsung Semiconductor Inc., a Korean electronics company
 * Silicon Systems Inc., an American company that produced integrated circuits.
 * Space Services Inc., a team of companies investigating new commercial opportunities in space
 * Strategic Simulations Inc, computer gaming company that produced war and simulation games from the mid-1980s to late 1990s.
 * Survey Sampling International, a global provider of sampling solutions in marketing research program
 * SSI Group, a healthcare revenue cycle company; see Rosa Lavín

Science and technology

 * Soil-structure interaction, the interaction between soil and structures (e.g. buildings), especially in seismic engineering
 * Solid State Interlocking, the brand name of a railway signalling system developed in the 1980s in the UK
 * Solid state ionics, the study of ionic-electronic and ionic conductors (solid electrolytes) and their uses
 * SteadyShot Inside, a sensor-based camera image stabilization system by Sony

Computing

 * Serializable snapshot isolation, a way to allow multiple concurrent transactions to see consistent information when making changes to a database
 * Server Side Includes, a server-side scripting language used on the Web
 * Self-sovereign identity, the user has a means of generating and controlling unique identifiers as well as some facility to store identity data.
 * Shared Source Initiative, a source-available software licensing scheme by Microsoft
 * Simple Sensor Interface protocol, a simple communications protocol designed for smart sensors
 * Single sign-in, a specialized form of software authentication
 * Single system image, a cluster dedicated operating system
 * Small-scale integration, a type of integrated circuit
 * Synchronous Serial Interface, a serial interface standard for industrial applications

Medicine

 * Stress–strain index, a measure of bone strength
 * Surgical site infection
 * Sliding scale insulin, fast- or rapid-acting insulin only given subcutaneously

Economics and government

 * Standing settlement instructions, payment processing and settlement information about financial institutions
 * Strategic sustainable investing, an investment strategy that recognizes financial value in transitional leadership towards sustainability
 * Supplemental Security Income, a United States federal government program
 * Scottish statutory instrument, a form of secondary or subordinate legislation in Scotland
 * Sensitive security information, a category of sensitive information under the US government's information sharing and control rules

Military and police

 * Selective Service Initiative, a form of military conscription in the United States
 * Senior station inspector, a rank in the Singapore Police Force
 * Shoulder sleeve insignia, formation insignia used by the United States Army
 * Soldier Support Institute, a U.S. Army organization
 * Staff Sergeant Instructor, an appointment in the British Army
 * State Security Investigations Service, former Egyptian agency
 * Strategic Studies Institute, the US Army War College institute for geostrategic and national security research and analysis
 * Attack Submarine (Diesel Air-Independent Propulsion) (hull classification symbol: SSI), a submarine classification type used by the US Navy
 * Subsecretaria de Inteligência, the Brazilian intelligence agency until 1995

Organizations

 * Sano Sansar Initiative, a global youth organization
 * Scuba Schools International, a diver training organization
 * Software Sustainability Institute, a UK-based, academic software organisation
 * Space Science Institute, an American nonprofit organisation based in Boulder, Colorado
 * Space Studies Institute, an American non-profit organization based in Mojave, California
 * Spastics Society of India, former name of Able Disable All People Together
 * Spatial Sciences Institute, a professional body in the Asia-Pacific region
 * Statens Serum Institut, the Danish State Serum Institute
 * Swedish Radiation Safety Authority (Statens strålskyddsinstitut), a Stockholm-based regulatory and research government agency
 * Students Supporting Israel, a network of pro-Israel student organizations in North America and the United Kingdom
 * Swedish Society for Interlingua, a society that encourages the active use of Interlingua in Sweden

Other uses

 * Socio-scientific issues, controversial social issues which relate to science
 * Solid State Ionics, a peer-reviewed scientific journal
 * Solid State Intelligence, a malevolent entity described by John C. Lilly
 * South Sandwich Islands, a chain of uninhabited volcanic islands in the South Atlantic Ocean, that is part of the South Georgia and the South Sandwich Islands British Overseas Territory
 * St. Simons Island, a barrier island on the coast of Georgia, US
 * Star of the Solomon Islands, the most senior award made by the government of the Solomon Islands
 * Sustainable Society Index, a tool for assessing the sustainability of 151 assessed countries