From Porniki

The Hymen is a covering over the entry to the vagina, which is usually broken during initial intercourse. Many girls refer to this hymen as their "virginity", although being a virgin is a lack of sexual intercourse, and not a strictly physical thing. Some girls do not have a hymen, other damage or break it during sports, riding a bicycle, or sometimes even intention (or accidentily) as they learn about masturbation during their developing years.

Hymen from Wikipedia

The hymen (or maidenhead; or in slang cherry) is a fold of mucous membrane which surrounds or partially covers the external vaginal opening. It forms part of the vulva, or external genitalia, and is present in all females at birth.[1][2] The most common formation of the hymen is crescentic or crescent-shaped, although several other formations are possible.[3] A woman's hymen is destroyed when she gives birth; she may be left with remnants called carunculae mytriformes or the hymen may be completely absent.[4]

The hymen has no known anatomical function. In societies which value chastity, the greatest significance of the hymen is a traditional belief that an intact hymen indicates a state of intact virginity. However, it is not possible to confirm that a woman or post-pubescent girl is a virgin by examining the hymen.[5] A physician routinely checks the appearance of the hymen of baby girls at birth, and again during all future pelvic examinations. In cases of suspected rape or sexual abuse a detailed examination of the hymen may be carried out, however the condition of the hymen alone is often inconclusive or open to misinterpretation, especially if the patient has reached puberty.[6]

The name hymen is from the Greek for membrane.[7] Hymen is also a name for the Greek God of marriage and weddings, Hymenaeus, but this name has a different root.[8]

Hymen. (2006, October 23). In Wikipedia, The Free Encyclopedia. Retrieved 19:56, October 24, 2006, from http://en.wikipedia.org/w/index.php?title=Hymen&oldid=83108476