To the contrary, here is what I found:

Pronunciation: 'brat
Function: noun
Etymology: perhaps from English dialect brat (coarse garment)
Date: circa 1505
1 a : CHILD; specifically : an ill-mannered annoying child b : an ill-mannered immature person
2 : the son or daughter of a career military person
- brat·ti·ness /'bra-tE-n&s/ noun
- brat·tish /'bra-tish/ adjective
- brat·ty /-tE/ adjective