There are 38 7-letter words that start with 'ser'.
Note: These 38 7-letter words that start with 'ser' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with seri, serv, sero, sere, serr, sera, serg, serm, serp, serf, serj, seru, serd, sers.
4-letter words start with 'ser' (4)