"Shark week," "Aunt Flo," "Carrie at the prom" — these are a few common nicknames for periods, according to Jennifer Weiss-Wolf, author of Periods Gone Public: Taking a Stand for Menstrual Equity. But the list is far from exhaustive: "There are something like 5,000 euphemisms for periods," she says.

Why all the code words? Society has become more open to talking about menstruation in recent years (in fact, NPR declared 2015 the "year of the period"), but periods are still a topic more often talked around than talked about. That can have consequences — like shame, undiagnosed medical conditions and lack of product innovation, to name a few.

Copyright 2018 NPR. To see more, visit http://www.npr.org/.