There are 4 13-letter words that start with 'est'.
| establishable | establishment | 
| estimableness | estrangements | 
Note: These 4 13-letter words that start with 'est' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with estr, esti, esta, este, esth, esto, estu.
5-letter words start with 'est' (2)