There are 12 words that start with 'radiat'.
| radiate | radiated | 
| radiates | radiator | 
| radiately | radiating | 
| radiation | radiative | 
| radiators | radiations | 
| radiational | radiationless | 
Note: These 12 words that start with 'radiat' are found from the USA & Canada version of the tournament Scrabble word list.