There are 10 words that start with 'irrat'.
| irrational | irrationals |
| irrationally | irrationalism |
| irrationalist | irrationality |
| irrationalisms | irrationalists |
| irrationalistic | irrationalities |
Note: These 10 words that start with 'irrat' are found from the USA & Canada version of the tournament Scrabble word list.