| Acronym | Meaning |
| TCOD | Total Chemical Oxygen Demand |
| TCPTP | T-cell Protein Tyrosine Phosphatase |
| TCR | T Cell Receptor |
| TCR | Temperature Coefficient Of Resistance |
| TCR | Total Chlorine Residual |
| TCS | Target Current Spectroscopy |
| TCS | Total Current Spectroscopy |
| TCSCF | Two-configuration Self-consistent Field Procedure |
| TCSM | Tropospheric Chemistry Systems Model |
| TCSPC | Time-correlated Single-photon Counting |
| TCVA | Total Culturable Virus Assay |
| TCXO | Temperature-compensated Crystal Oscillator |
| TD | Thermal Desorption |
| TD | Transmembrane Distillation |
| TD-CAC | Time Dependent-coupled Arrangement Channel (method For Calcns. On Reactive And Dissociative Collisions) |
| TDA | Tamm-Dancoff Approximation |
| TDA-2PH | Two-particle One Hole Tamm-Dancoff Approximation |
| TDC | Time-to-Digital Converter |
| TDC | Top Dead Center |
| TDCC | Time-dependent Close-coupling |
| TDCC | Time-dependent Coupled-cluster |
| TDCHF | Time-dependent Coupled Hartree-Fock |
| TDCP-HFR | Time-dependent Coupled Perturbed Hartree-Fock-roothan Approach |
| TDCR | Triple To Double Coincidence Ratio |
| TDCS | Total Dissolved And Colloidal Solids |
| TDCS | Triple Differential Cross Section |
| TDD | Telecommunications Device For The Deaf |
| TDDB | Time Dependent Dielectric Breakdown |
| TDDFT | Time-dependent Density-functional Theory |
| TDEMSE | Time-dependent Effective Mass Schroedinger Equation |
| TDFGH | Time-dependent Fourier Grid Hamiltonian (method) |
| TDFM | Two-surface Dirac-Frenkel-Mclachlan (variational Method) |
| TDGC/MS | Thermal Desorption Gas Chromatography/mass Spectrometry |
| TDGI | Time-dependent Gage-invariant (quantum Calcn. Method) |
| TDH | Time-dependent Hartree Theory |
| TDHF | Time-dependent Hartree-Fock Method |
| TDHG | Time-dependent Hartree Grid (quantum Method) |
| TDI | Tolerable Daily Intake |
| TDI | Toluene Diisocyanate [mixt. Of Isomers] |
| TDKS | Time-dependent Kohn-Sham (d.-functional Operator Equation) |
| TDL | Tunable Diode Laser |
| TDLAS | Tunable Diode Laser Absorption Spectroscopy |
| TDLDA | Time-dependent Local-density Approximation |
| TDLS | Tunable Diode Laser Spectrometry |
| TDM | Therapeutic Drug Monitoring |
| TDM | Time-division Multiplexing |
| TDM | Truncated Diagonalization Method |
| TDMCSCF | Time-dependent MC-SCF |
| TDMF | Time-dependent Mean Field |
| TDMO | Time-dependent Molecular Orbital |