sanitary shorts; period panties
Underwear designed for menstruation, often with a built-in absorbent layer or waterproof lining. The term is a wasei-eigo compound from 'sanitary' and 'shorts'.
Lately, even sanitary shorts are coming in more stylish designs.
When traveling, I take several pairs of period panties.
Variant with interpunct; less common in everyday writing.
Wasei-eigo (Japanese-made English) from 'sanitary' + 'shorts'. Not a direct borrowing from English, where 'sanitary shorts' is not a standard term.