Wannabe teenagers that aren't old enough to be considered teens.

Usually girls that tart themselves up to look like whores around the age of 8-11. Absolutely horrible

Tell tale signs of being a tweenie are flip phones, big hoopy earrings and awful, awful blue eye shadow all before the age of 13.

A girl under 13 acting like a whore. Such as reveling clothes, stupid makeup, big hoop earrings and normally thinks they're sexy or so popular.

Tweenie can be a compliment. You are considered a tweenie when you act or say something corny, hilar, silly, or cheesy. Tweenie can be referred to as someone or something/ some action.