There are 17 words that start with 'estra'.
| estral | estray | 
| estrays | estragon | 
| estrange | estrayed | 
| estradiol | estragons | 
| estranged | estranger | 
| estranges | estraying | 
| estradiols | estrangers | 
| estranging | estrangement | 
| estrangements | |
Note: These 17 words that start with 'estra' are found from the USA & Canada version of the tournament Scrabble word list.