This word refers to a person that is easy to knock out during a fight.
"He's got a glass chin that lad. I saw him take one punch from a 4ft midget and he went down straight away!"
by TheCoroner September 09, 2005
Someone who has a weak chin or can't take a punch.
"How's it going?" "Mmmbad" "Did I remind you that you have a glass chin?"
by Pat Rorke September 02, 2008