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2.
Noun denoting the offspring conceived by a married woman while her husband is away for a period of months or years; e.g., at war or in the joint.
Moe: I don't understand how my wife had a baby a month ago. I mean, I'd been away for two years!

Joe: Well, Moe, that kid's a grudgebaby. Somebody had it in for you.
by Ernest Peabody August 01, 2006
 
1.
It's an asian kid who hides in your attic. And wears mascara. And is albiano.
Dude, fuck why are you in my house you grudge baby?

You fucking pail you look like a grudge baby.
by thats what she said! May 08, 2007