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1.
The father of the child (or children) of a divorced couple in which the mother has since re-married.
Hey, who is that creepy guy in the minivan that's watching us play softball?
Oh, him? He's just my yesterdaddy. He's just a little depressed since my mom married Biff.
by yesterdaddy June 18, 2009
 
2.
noun - Term used for the guy I dated last year.
"Who's that? He's hot!"
"Oh him? He's my Yesterdaddy."
by ActingBoy September 04, 2011