TSI

TSI may refer to:

Science, technology and engineering

 * Technology Schools Initiative
 * Thyroid stimulating immunoglobulin
 * Time-Slot Interchange, communications network switches
 * Total solar irradiance received at top of atmosphere
 * Triple sugar iron test or TSI slant, of a microorganism's ability to ferment sugars
 * Trophic state index of plant nutrients in waterbodies
 * Turbo fuel stratified injection, a VW engine trademark TSI or TFSI

Standards, and standards organisations

 * Technical Specifications for Interoperability within European railways
 * Trading Standards Institute, a British professional association
 * Trustworthy Software Initiative, UK
 * Turkish Standards Institution, a public standards organization in Turkey

Companies

 * TekSavvy Solutions Inc., Canadian telecommunications company
 * Telesensory Systems Inc., maker of products for the blind
 * Town Sports International, an operator of fitness facilities

Organisations

 * The Seasteading Institute, for creating dwellings on seaborne platforms in international waters
 * Three Seas Initiative, European intergovernmental group

Media and entertainment

 * Televisione svizzera di lingua italiana, Swiss Italian-language TV

Other uses

 * Texas Success Initiative, a guide for developmental education to ensure college readiness in the state of Texas
 * Time in Turkey, generally abbreviated with its usage in Turkish, Türkiye Saati İle
 * Tissue saturation index in medical near-infrared spectroscopy
 * True strength index of financial markets
 * Trauma symptom inventory, a psychological assessment instrument