| Trinitrotoluene | Trinity | Trinity (nuclear test) |
| Trinity College, Dublin | Trinity, North Carolina | Triode |
| Trion, Georgia | Trionychidae | Trionyx triunguis |
| Triops | Triopsidae | Triose |
| Trioxidane | Trioxsalen | Triphenyl phosphate |
| Triphenylarsine | Triphenylphosphine | Triplarideae |
| Triplaris | Triplaris americana | Triplaris caracasana |
| Triplaris fulva | Triplaris longifolia | Triplaris peruviana |
| Triple DES | Triple Entente | Triple H |
| Triple point | Triple product | Triple product rule |
| Triple spiral | Triple-alpha process | Triplegia |
| Tripod (photography) | Tripol libya | Tripoli Cathedral |
| Tripoli Grand Prix | Tripoli International Airport | Tripoli International Fair |
| Tripoli Lebanon | Tripoli Tower | Tripoli, Lebanon |
| Tripolitanian lira | Tripp, South Dakota | Tripp, Wisconsin |
| TRIPS Agreement | Triptan | Tripwire (تريب-واير) |
| Tripy Makonda | Triquetral bone | Triradiate cartilage |
| Triruthenium dodecacarbonyl | Tris(2,3-dibromopropyl) phosphate | Tris(2-chloroethyl) phosphate |
| Tris(8-hydroxyquinolinato)aluminium | Tris(benzyltriazolylmethyl)amine | Trish Stratus |
| Triskelion | Trismus | Trisodium citrate |
| Trisomic | Trisomy 21 | Trisomy 9 |
| Trisquel | Tristan Bernard | Tristan da Cunha |
| Tristan Thompson | Tristan Tzara | Tristan Wilds |
| Tristar Air | TriStar Pictures | Tristar RAF |
| Tristramella magdelainae | Trita Parsi | Tritellurium dichloride |
| Tritheism | Tritiated water | Triticeae |
| Triticum aestivum | Triticum dicoccum | Triticum durum |
| Triticum monococcum | Triticum spelta | Triticum turanicum |
| Tritium | Tritium illumination | Tritriacontane |
| Trium Mondo | Triumph Motor Company | Triumph of the Will |
| Triumph T140 TSX | Triumph T140W TSS | Triumph Thunderbird (2009) |
| Triumph Thunderbird 900 | Triumph Tiger 80 | Triumph Tiger 955i |
| Triumph Tiger Cub | Triumph Tiger T110 | Triumphal arch |
| Trivandrum International Airport | Trivia | Trivium |
| Trivolzio | Trixie (film) | Triz |
| TRIZ | TRNA | Troškūnai |
| Troène | Trochidae | Trochilidae |
| Trochlear fovea | Trochlear nerve | Troels Rasmussen |
| Trofeo Alfredo Di Stéfano | Trofim Lysenko | Trogia inaequalis |
| Troglodytes troglodytes | Troglodytidae | Trogon |
| Trogonidae | Trogoniformes | Troian Bellisario |
| Troika (driving) | Troisvaux | Trojan |
| Trojan Horse | Trojan horse (computing) | Troll |
| Trolleybus | Trolling | Trolls (film) |
| Trollstigen | Tromantadine | Trombicula |
| Trombicula autumnalis | Trombiculidae | Trombiculinae |
| Trombiculoidea | Trombiculosis | Trombidiformes |
| Tromello | Trommald, Minnesota | Trompe |
| Trompe-l'œil | Tromsø | Tromsø IL |
| Tromso | Tron: Legacy | Trond Sollied |
| Troodontidae | Tropaeolaceae | Tropaeolum |
| Tropaeolum argentinum | Tropaeolum asplundii | Tropaeolum atrocapillare |
| Tropaeolum beuthii | Tropaeolum bicolor | Tropaeolum capillare |
| Tropaeolum jilesii | Tropaeolum kingii | Tropaeolum majus |
| Tropaeolum minus | Tropaeolum pentagonum | Tropaeolum peregrinum |
| Tropaeolum polyphyllum | Tropaeolum purpureum | Tropaeolum seemannii |
| Tropaeolum smithii | Tropaeolum speciosum | Tropaeolum stipulatum |
| Tropaeolum tricolor | Tropaeolum trilobum | Tropaeolum tuberosum |
| Tropaeolum umbellatum | Trope (literature) | Trophoblast |
| Trophoblastic neoplasm | Trophy (countermeasure) | Tropic Thunder |
| Tropic, Utah | Tropical climate | Tropical cyclone |
| Tropical disease | Tropical fish | Tropical medicine |
| Tropical rainforest | Tropical rainforest climate | Tropical spastic paraparesis |
| Tropico | Tropico 5 | Tropicos |
| Tropinota squalida | Tropiocolotes | Tropiocolotes bisharicus |
| Tropiocolotes nattereri | Tropiocolotes nubicus | Tropiocolotes steudneri |
| Tropiocolotes tripolitanus | Troposphere | Trosky, Minnesota |
| Trotwood, Ohio | Troubadour | Troubleshooting |
| Trout Lake Township, Michigan | Trout Valley, Illinois | Troutdale, Oregon |
| Trovo | Trowbridge Township, Michigan | Troxipide |
| Troy | Troy (film) | Troy Baker |
| Troy Daniels | Troy Grove, Illinois | Troy ounce |
| Troy Township, Michigan | Troy, Illinois | Troy, Kansas |
| Troy, Michigan | Troy, Missouri | Troy, Montana |
| Troy, Sauk County, Wisconsin | Troy, St. Croix County, Wisconsin | Troy, Tennessee |
| Troy, Texas | Troy, Vermont | Troy, Walworth County, Wisconsin |
| Troyca | Trstená | TRT |
| TRT6 | Truchtersheim | Trucial States |
| Truck | Truck Robinson | Truck scale |
| Truckton, Colorado | Trudeau Institute | True airspeed |
| True Crime :streets of LA | True Crime: New York City | True Cross |
| True Detective (TV series) | True Grit (1969 film) | True Grit (2010 film) |
| True Lies | True Path Party | True ribs |
| True self and false self | True Tears | True, Wisconsin |
| TrueCrypt | Truesdale, Iowa | Truesdale, Missouri |
| TruForm | Truman Capote | Truman Doctrine |
| Truman, Minnesota | Trumann, Arkansas | Trumansburg, New York |
| Trumbull, Nebraska | Trump International Hotel and Tower (Chicago) | Trump Taj Mahal |
| Trumpet | Trumpler 1 | Trumpler 16 |
| Trumpler 2 | Truncal obesity | Trunk (automobile) |
| Trunk to Cairo | Truro, Iowa | Truss arch bridge |
| Truss bridge | Trust (game show) | Trust (social sciences) |
| Trust management (managerial science) | Trust Territory of Somaliland | Trusted third party |
| Trusty Bell | Truth | Truth or Consequences, New Mexico |
| Truth serum | Truth value | Truvada |
| Truxton, Missouri | TRX2 | Trygve Haavelmo |
| Tryngites | Tryngites subruficollis | Trypanosoma |
| Trypanosoma brucei | Trypanosoma evansi | Trypanosomatida |
| Trypanosomatidae | Trypanosomatina | Trypsin |
| Trypsinogen | Tryptamine | Trypticase soy agar |
