There are 10 words that start with 'tetrah'.
| tetrahedra | tetrahedral |
| tetrahedron | tetrahymena |
| tetrahedrite | tetrahedrons |
| tetrahymenas | tetrahedrally |
| tetrahedrites | tetrahydrofuran |
Note: These 10 words that start with 'tetrah' are found from the USA & Canada version of the tournament Scrabble word list.