There are 14 words that start with 'irrad'.
| irradiant | irradiate | irradiance |
| irradiated | irradiates | irradiator |
| irradiances | irradiating | irradiation |
| irradiative | irradiators | irradicable |
| irradicably | irradiations | |
Note: These 14 words that start with 'irrad' are found from the USA & Canada version of the tournament Scrabble word list.