Source : Webster's Revised Unabridged Dictionary (1913)

Schoolmistress \School"mis`tress\, n.
   A woman who governs and teaches a school; a female
   school-teacher.

Source : WordNet®

schoolmistress
     n : a woman schoolteacher (especially one regarded as strict)
         [syn: {schoolmarm}, {schoolma'am}, {mistress}]