There are 18 words that start with 'downt'.
| downtick | downtime | downtown | 
| downtrod | downturn | downthrow | 
| downticks | downtimes | downtowns | 
| downtrend | downturns | downthrows | 
| downtowner | downtrends | downtowners | 
| downtrended | downtrodden | downtrending | 
Note: These 18 words that start with 'downt' are found from the USA & Canada version of the tournament Scrabble word list.