hymen

The hymen or vaginal corona is a tissue, usually doughnut-shaped, inside the vagina. They don't "break" or bleed, but some of the hymen can stretch or tear. It is normal for some of the hymen to wear away due to normal activities such as bathing, masturbation, even just moving around or stretching. Contrary to popular belief, it is actually pretty unlikely that a hymen will be damaged by riding a bike or a horse, because all these activities really do is put pressure on the perineum, not interfere with the vagina itself. It does not completely cover the vagina; if it did, menstruation would be impossible for girls with intact hymens. By the time full PVI occurs, the hymen is (usually) already mostly worn away.

A thin, elastic membrane stretched partly or completely across the entrance of the vagina (vestibule). It has no known biological function. An intact hymen has long and erroneously been considered the hallmark of female virginity . The presence or absence of the hymen is no proof of virginity or its opposite; the hymen can be broken in the normal course of physical activities when the body is stretched strenuously, as in athletics, sports or exercises. It may be absent, small, thin and pliant, or, more rarely, tough and dense, completely blocking the vaginal entrance; it varies in size, shape and thickness from woman to woman . If it is too resistant to tearing it may require a small surgical incision, hymenotomy , or even removal, hymenectomy , before vaginal intercourse can take place .

A membranous fold of tissue that partly or completley occludes the external vaginal orifice.

(n.) "cherry"- the mucus membrane stretching across the opening of the vagina.

A membrane covering the vaginal opening of a virgin.

the piece of skin over the opening of a vagina that boys have to break through when they deflower their girl.

What you would say when you walk up on a group of men...
"HYMEN"