There are 9 15-letter words that start with 'tri'.
| triangularities | trichomonacidal |
| trichomonacides | trifluoperazine |
| trigonometrical | trihalomethanes |
| trinitrotoluene | trisoctahedrons |
| trivializations | |
Note: These 9 15-letter words that start with 'tri' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with tric, trip, tria, tris, trib, trig, trit, trim, tril, trif, trin, triv, triu, trie, trio, trih, trid, trij, trir, trik, triw, triq.
4-letter words start with 'tri' (4)