A girl and/or woman who is obsessed with a man in which they can never have. Most of the time this is with fictional characters such as Ikuto Tsukiyomi from Shugo Chara or such as L Lawliet from Death Note, although there are times when girls obsess over celebrities, such as Justin Bieber. However, there are a select handful of girls who's favorite anime character/actor is a man, but isn't necessarily a "fangirl", such as myself.
A fangirl is a girl who is an annoying fan to something and/or somebody. They act in an exaggerate manner. A great example is how Ino and Sakura are to Sasuke from the animeNaruto.
Fangirl: I wuv him! I want to marry him! He's sooo cute!! ^^ *glomps*
little airheaded teens that obsess over unsubstantial stuff ranging from flashy clothing lines to cheapfanfiction to gay male celebs.
fangirl1: OMFG!!!!!!!111 JOE JONAS IS HAWT!!!!!!11
fangirl2: totally..... <3<3<3
fangirl3: back of girls, hez mine!!!!
fangirl1: have u read twilight??? isnt it so beautifully romanttic?????
fangirl2: ooh yes....smeyer is a genius
fangirl1: lyk, did u knw there r twihaters out there???
fangirl2: OMEC OMEC whtz wrong wid dem??? i'll get my vamps to kill them!!!!
Very commonly misunderstood to be hyper-active and stalker-ish. But in fact, they are mostly peaceful introverts who don't have the courage to ask anything from any person in real life, and are most likely to live inside the internet. They may seem like a quite breed of cats at first sight, but if you insult them, remember that they have already planned 72 ways to murder you, 25 ways to kidnap you and 16 different ways to hide your body without getting caught by the law. This is mostly inspired by their obsession with a certain fandom.
Closely related to Nerds, at times. Male version of a Fangirl is known as Fanboy, and they're very scarce but existent nonetheless.
Jaz: Oh my gods! I just killed my ex-boyfriend, it was an accident I swear! What do I do now??
Sadie: Gods? Are you in the PJO fandom? It's okay, I'm a Fangirl myself. I watch Supernatural, CSI and Boston Legals. You've come to the right place, follow me.
Someone who usually lives off Nutella. They are not always social and go on tumblr. They cry a lot and are crazy. Their vocabulary consists mainly of "I can't even." "ASKDEFGGHLGDF." And sobbing.