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.
Jen fucked me 20 times yesterday, def a nymphomaniac, im tired, she needs tranquilisers