There are 13 words that start with 'hygr'.
| hygrostat | hygrograph | 
| hygrometer | hygrophyte | 
| hygrostats | hygrographs | 
| hygrometers | hygrometric | 
| hygrophytes | hygrophytic | 
| hygroscopic | hygrophilous | 
| hygroscopicity | |
Note: These 13 words that start with 'hygr' are found from the USA & Canada version of the tournament Scrabble word list.