There are 78 13-letter words that start with 'mis'.
Note: These 78 13-letter words that start with 'mis' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with misc, miss, misa, mist, misp, misd, mise, misr, misb, misl, misf, misg, mism, miso, misi, mish, misk, misu, misj, misn, misw, misq, misv, misy.
4-letter words start with 'mis' (4)