There are 13 words that start with 'trian'.
| triangle | triangled |
| triangles | triangular |
| triangulate | triangularly |
| triangulated | triangulates |
| triangularity | triangulating |
| triangulation | triangulations |
| triangularities | |
Note: These 13 words that start with 'trian' are found from the USA & Canada version of the tournament Scrabble word list.