There are 9 words that start with 'irref'.
| irreflexive | irrefutable |
| irrefutably | irreformable |
| irrefragable | irrefragably |
| irrefutability | irreformability |
| irrefragability | |
Note: These 9 words that start with 'irref' are found from the USA & Canada version of the tournament Scrabble word list.