TSI
# 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 (transl. With Turkey Time)
* Tissue saturation index in medical near-infrared spectroscopy
* True strength index of financial markets
* Trauma symptom inventory, a psychological assessment instrument
