mistress vs schoolmistress

mistress and schoolmistress both are nouns.

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

As nouns, mistress and schoolmistress are synonyms defined as:

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

Other synonyms of mistress include schoolma'am, schoolmarm.

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