From Longman Dictionary of Contemporary Englishhousemistresshouse‧mis‧tress /ˈhaʊsˌmɪstrɪs/ noun [countable] especially British EnglishSES a female teacher who is in charge of one of the houses (=groups of children of different ages) in a school → housemaster
Examples from the Corpus
housemistress• The housemistress even presented me with a glass of milk at lunch. 