There are 16 9-letter words that start with 'radi'.
| radiances | radiantly | radiately | 
| radiating | radiation | radiative | 
| radiators | radically | radicands | 
| radicated | radicates | radicchio | 
| radicular | radiogram | radiology | 
| radionics | ||
Note: These 16 9-letter words that start with 'radi' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with radio, radic, radia, radiu, radis, radix, radii.
5-letter words start with 'radi' (3)