There are 12 words that start with 'regret'.
| regret | regrets |
| regretful | regretted |
| regretter | regretters |
| regretting | regretfully |
| regrettable | regrettably |
| regretfulness | regretfulnesses |
Note: These 12 words that start with 'regret' are found from the USA & Canada version of the tournament Scrabble word list.