A person (historically used to refer to women, but the word means both men and women) who has an abnormally high sex drive and craves sex nearly all the time.
Hypersexuality: a female whose sex drive is obsessively high. Considered a mental illness, coloqiually means a horny girl. Not to be confused with slut or skank where one's sexual dignity is pathetically low, nymphomania is simply related to an abnormally high sex drive.