| Trifolium incarnatum | Trifolium lappaceum | Trifolium ligusticum |
| Trifolium micranthum | Trifolium nigrescens | Trifolium ochroleucon |
| Trifolium palaestinum | Trifolium pauciflorum | Trifolium pilulare |
| Trifolium plebeium | Trifolium pratense | Trifolium purpureum |
| Trifolium repens | Trifolium resupinatum | Trifolium salmoneum |
| Trifolium spumosum | Trifolium squamosum | Trifolium squarrosum |
| Trifolium stellatum | Trifolium subterraneum | Trifolium suffocatum |
| Trifolium sylvaticum | Trifolium vavilovii | Trifon Ivanov |
| Triforce | Trifurcula ridiculosa | TRIGA |
| Trigeminal nerve | Trigeminal nerve nuclei | Trigeminal neuralgia |
| Trigg County, Kentucky | Trigla lyra | Triglyceride |
| Triglyph | Trigonal | Trigonal crystal system |
| Trigonal planar molecular geometry | Trigonella | Trigonella foenum-graecum |
| Trigonometric function | Trigonometric functions | Trigonometric integral |
| Trigonometric polynomial | Trigonometric substitution | Trigonometric tables |
| Trigonometry | Trigonometry table | Trigonostigma heteromorpha |
| Trihydrogen cation | Triiodothyronine | Trijet |
| Trilaminar blastocyst | Trilateral Commission | Trilateration |
| Trilinear coordinates | Trillium Model | Trilobita |
| Trilobite | Trilobitomorpha | Trilogy |
| Trimbach, Bas-Rhin | Trimbelle, Wisconsin | Trimble County, Kentucky |
| Trimble, Ohio | Trimble, Tennessee | Trimenia |
| Trimenia arfakensis | Trimenia bougainvilleensis | Trimenia grandifolia |
| Trimenia macrura | Trimenia marquesensis | Trimenia moorei |
| Trimenia myricoides | Trimenia neocaledonica | Trimenia nukuhivensis |
| Trimenia papuana | Trimenia weinmanniifolia | Trimeniaceae |
| Trimethylaluminium | Trimethylaminuria | Trimipramine |
| Trimix | Trimix (breathing gas) | Trimont, Minnesota |
| Trin. | Tringa erythropus | Tringa glareola |
| Tringa guttifer | Tringa nebularia | Tringa ochropus |
| Tringa stagnatilis | Tringa totanus | Trinidad and Tobago |
| Trinidad and Tobago dollar | Trinidad, Colorado | Trinità dei Monti |
| 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 |
