big girl

Short definition from Wiktionary

Noun

1. 1
   Used other than figuratively or idiomatically: see big, girl.
2. 2
   An adult female.
3. 3
   An older girl or grown-up girl; a girl who is no longer an infant.
4. 4
   A timid, weak or effeminate boy or man.
5. 5
   A female supposed to behave as a responsible adult.
6. 6
   A woman who is overweight.