Delph: Hmm - perhaps this starts to lend credibility to the theory that it comes from the East, then?
I was thinking maybe so, too. However, I did a little research and found from a cooking blog a bit of information. I posted this on the other thread about if there is a social or class distinction between the two words for grandmother.
"Also, I wanted to explain why it's called "Busia's" Sauerkraut. Modern day Poles call their Grandmothers "Babcia", however, as my husband's family is Polish by a couple of generations, prior to The Great War, in the Ukraine, Grandmothers were called "Babusia", shortened to "Busia", and sometimes twisted by accent and time to "Buzia" (which actually means "mouth" but I am just glad that they try and are close)..."
polishmamaontheprairie.blogspot.com/2010/11/thanksgiving-and-remembering-our-past.html
This information also points to the east, but a few others on PF also say that Babusia was used and still is to a degree in Poland. I think I also heard it was prevalent in the highlands. It's just a shortened form of Babusia, but in America the spelling and pronounciation have changed along the way.
I grew up knowing a lot of Polish words, but I had no idea how they were spelled. My grandmother could read and write in Polish, my mother could speak Polish. And so it goes within a few generations. It is only the past few years that I have learned how to sound out words and spell them.