A female preceptor, or provider of moral instruction(noun)
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Use "preceptress" in a sentence
"And a very great proof that the prince is good is when his people are good, because the prince's life is law and preceptress to his subjects, and upon his behaviour all the others must needs depend ...."
"He studied with the Christian Brothers, Benedictines and Marists, as well as with his preceptress, Professor María Teresa Angulo, from Madrid."
"She was not a rigorous old moralist, nor, perhaps, a very wholesome preceptress for youth."