Mentrix

Olga had indeed learned that the church had appointed certain days and seasons for fasting, but thought she had herself fasted in a fashion, she had never suspected that she was imitating Christ, and she had never been told that the oil was a necessary part of the observance. Anxious to please her new mentrix she tried to swallow the nasty stuff, but the flesh was weak and, moreover, rebellious; and thus the first experiment in religious discipline proved a failure.

Finally, as women scholars — at every career level — we must never underestimate our value as mentors — or mentrices.

But shouldn't the verb form be "ment"? The mentor mented his mentees. / His wife, also a mentrix, or one of his daughters, both mentrices, took over menting when he was away.

Each girl is instructed by a mentrix (nacimbusa, plural banacimbusa), who is helped by other women. Apart from being themselves initiated and authorized to perform these rites, the mentrices must be women who are well-respected in society, who maintain a good standard of family life, and whose conduct is above reproach.

One of my mentors (mentrixes? mentrices?), fantasy-horror novelist Chelsea Quinn Yarbro, who proudly claims Finnish heritage*, asserts quite strongly that the Finns are not Scandinavians. They certainly aren't Slavs either.