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menstrual cup

n. A receptacle worn inside the vagina during menstruation to collect menstrual fluid.

Wikipedia
Menstrual cup

A menstrual cup is a type of feminine hygiene product which is usually made of medical grade silicone, shaped like a bell and is flexible. It is worn inside the vagina during menstruation to catch menstrual fluid ( blood). About every 4–12 hours (depending on the amount of flow), the menstruating woman removes the menstrual cup from her vagina, empties the collected menstrual blood into a toilet or sink, washes the cup under running water and inserts it again. At the end of the monthly period, the cup can be sterilized, usually by boiling in water. Unlike tampons and pads, the cup collects menstrual fluid rather than absorbing it.

Manufacturers have different recommendations for when to replace the cups, but in general they can be reused for five years or so.