From Longman Dictionary of Contemporary Englishschoolmistressschool‧mis‧tress /ˈskuːlˌmɪstrɪs/ noun [countable] British English SESBOa female teacher, especially in a private school (=one that parents pay to send their children to)
Examples from the Corpus
schoolmistress• Ellen, a schoolmistress, had tried to help Peter in raising him.• To him, a schoolmistress was a crusty Old Maid in a liberty bodice and lisle stockings.• After three days, the schoolmistress in charge phoned. 