Wiktionary
n. A device that inserted into the vagina during sexual intercourse as a barrier contraceptive to reduce the risk of sexually transmitted infections and unintended pregnancy.
Wikipedia
A female condom (also known as a femidom) is a device that is used during sexual intercourse as a barrier contraceptive to reduce the risk of sexually transmitted infections (STIs—such as gonorrhea, syphilis, and HIV, though its protection against them is inferior to that by male condoms) and unintended pregnancy. Invented by Danish MD Lasse Hessel, it is worn internally by the female partner and provides a physical barrier to prevent exposure to ejaculated semen or other body fluids. Female condoms can be used by the receptive partner during anal sex.
The female condom is a thin, soft, loose-fitting sheath with a flexible ring at each end. They typically come in various sizes. For most vaginas, a moderately sized condom is adequate; women who have recently given birth should try a large size first. The inner ring at the closed end of the sheath is used to insert the condom inside the vagina and to hold it in place during intercourse. The rolled outer ring at the open end of the sheath remains outside the vagina and covers part of the external genitalia.