There are 17 words that start with 'underr'.
| underran | underrun |
| underrate | underripe |
| underruns | underrated |
| underrates | underreact |
| underrating | underreacts |
| underreport | underreacted |
| underreports | underrunning |
| underreacting | underreported |
| underreporting | |
Note: These 17 words that start with 'underr' are found from the USA & Canada version of the tournament Scrabble word list.