TDI may refer to: Science and technology Tolerable daily intake, in toxicology Toluene diisocyanate, an organic chemical Time delay and integration, timing synchronization in an image sensor Tissue Doppler imaging, a medical ultrasound technology Tabbed document interface, a type of graphical user interface Total dual integrality, a property of matrices in mathematical optimization Transport Driver Interface, used by NT series Windows to abstract level 7 APIs into a common protocol for the Transport Protocol layer Telecom data intelligence, ability to extract detailed customer profiling data Trophic Diatom Index, water quality and ecological status; see Sattal Turbocharged Direct Injection, a diesel engine design used in cars and light vans made by Volkswagen Group Organizations Technical Diving International, a technical diving organization Telecommunications for the Deaf, Inc., a nonprofit organization promoting telecommunications devices for the deaf Texas Department of Insurance The Dartmouth Institute for Health Policy and Clinical Practice, a subsidiary of Dartmouth College Transportation Displays, Inc., a unit of Outfront Media Entertainment Total Drama Island, an animated reality series Tangerine Dream Independent, the record label belonging to Edgar Froese