Jo Livingstone in Book Forum:
AMONG THE OLDEST REFERENCES to menstruation in literature is in the book of Genesis, in a story about a lie. Rachel stole her father’s household gods, it goes, and when he came to retrieve them, she threw a covering over the objects and sat on it. She couldn’t stand, she apologized to her father, because she was in “the way of women.” At the end of the sixteenth century, an English clergyman clarified in his guide to Genesis that Rachel wasn’t pretending to be incapable of standing, just uncomfortable, due to her “monethly custome,” an ancestor to our contemporary “period.” As Jenni Nuttall explains in her new book Mother Tongue: The Surprising History of Women’s Words, “period” has been in use to name a quantity of time since the Middle Ages, but “only at the end of the seventeenth century”—so, a little after the clergyman’s time—“does the phrase ‘monthly period’ appear in medical books as a name for menstruation.”
More here.