There are 12 words that start with 'humidi'.
| humidify | humidity |
| humidified | humidifier |
| humidifies | humidistat |
| humidities | humidifiers |
| humidifying | humidistats |
| humidification | humidifications |
Note: These 12 words that start with 'humidi' are found from the USA & Canada version of the tournament Scrabble word list.