schoolmistress vs mistress

schoolmistress and mistress both are nouns.

Word	Noun	Adjective	Verb	Adverb
schoolmistress	Yes	No	No	No
mistress	Yes	No	No	No

As nouns, schoolmistress and mistress are synonyms defined as:

schoolmistress and mistress: a woman schoolteacher (especially one regarded as strict)

Other synonyms of schoolmistress include schoolma'am, schoolmarm.

schoolmistress (noun)	mistress (noun)
a woman schoolteacher (especially one regarded as strict)	a woman master who directs the work of others
	an adulterous woman; a woman who has an ongoing extramarital sexual relationship with a man
	a woman schoolteacher (especially one regarded as strict)