| Acronym | Meaning |
| TGMA | Task Group Of Metal Accumulation |
| TGN | Trans-Golgi Network |
| TGRS | Transient Gamma-Ray Spectrometer |
| TGSCC | Transgranular Stress-corrosion Cracking |
| TGTF | Trigonometric Gaussian-type Function |
| TGVBA | Target Generalized Valence Bond Approximation |
| TH | Total Hardness [of Water] |
| THAA | Total Hydrolyzable Amino Acids |
| THC | Total Hydrocarbon |
| THCP | Total Hazard Control Plan |
| THDM | Translucent Humic Degradation Matter |
| THEED | Transmission High-energy Electron Diffraction |
| THEES | Total Human Environmental Exposure Study |
| THEL | Tactical High Energy Laser |
| THESEO | Third European Stratospheric Experiment On Ozone |
| THFA | Target Hartree-Fock Approximation |
| THFFF | Thermal Field-flow Fractionation |
| THG | Third Harmonic Generation |
| THGA | Transversely Heated Graphite Atomizer |
| THGF | Trigonometric Hermite Gaussian Function |
| THM | Traveling Heater Method |
| THM | Transcorrelated Hamiltonian Method |
| THMFP | Trihalomethane Formation Potential |
| THRASH | Thorough High Resolution Analysis Of Spectra By Hornf1fs |
| THTR | Thorium High Temperature Reactor |
| TIA | Transient Ischemic Attack |
| TIARA | Takasaki Ion Accelerator For Advanced Radiation Application |
| TIAS | Technology Investment Assessment Screen |
| TIC | Total Inorganic Carbon |
| TIC | Total Ion Current |
| TICS | Time Reversal Invariant Closed Shell (type Of Hartree-Fock Wave Function) |
| TICT | Twisted Intramolecular Charge Transfer |
| TID | Thermionic Ionization Detector |
| TID | Traveling Ionospheric Disturbance |
| TIE | Toxicity Identification Evaluation |
| TIG | Tungsten Inert Gas (welding) |
| TIGER | Triangulation-Identification For The Genetic Evaluation Of Risk |
| TIGER | Technique For Importing Greater Evolution Resolution In Multidimensional NMR |
| TIGR | The Institute For Genomic Research |
| TIGRA | Thermostimulated Inert Gas Release Analysis |
| TIL | Tumor Infiltrating Lymphocytes |
| TILIBS | Time-integrated Laser Induced Breakdown Spectroscopy |
| TIMAS | Toroidal Imaging Mass-Angle Spectrograph |
| TIME | Temporally Integrated Monitoring Of Ecosystems |
| TIME | Transferred Ionized Molten Energy Process (for Metal Arc Welding) |
| TIME | Test, Inspect, Measure, And Evaluate |
| TIMI | Thrombolysis In Myocardial Infarction |
| TIMP | Tissue Inhibitors Of Metalloproteinase |
| TIMS | Thermal Infrared Multispectral Scanner |
| TIMS | Technical Information Management System |