There are 19 10-letter words that start with 'sim'.
Note: These 19 10-letter words that start with 'sim' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with simp, simu, simo, simi, sima, simm, siml, simn, sims.
4-letter words start with 'sim' (3)