There are 13 words that start with 'diagn'.
| diagnose | diagnosed |
| diagnoses | diagnosis |
| diagnosing | diagnostic |
| diagnosable | diagnostics |
| diagnoseable | diagnostical |
| diagnostician | diagnostically |
| diagnosticians | |
Note: These 13 words that start with 'diagn' are found from the USA & Canada version of the tournament Scrabble word list.