A pratling Nurse is a better Tutrix to her foster-child.
Didascalocophus, George Dalgarno (1680)

I speculate that after the word dominatrix became popular in people’s vocabulary, the “-trix” suffix became less popular. “-tress” and “-trice” have taken its place. It’s a shame really, now we don’t know many words to use that X with while playing Scrabble.

Maybe someone can pick this word up to describe their dominatrix-style tutoring program. College boys would surely study for all their tests.

Alternatively, if you are slightly better than a one-trick-pony, you’re a tutrix.

Now for a game of Scrabble. Oh please, oh please Scrabble Gods, let me get an X!