Piotr writes:
It's the genitive of bóg, a masculine noun. Like English
God, Polish Bóg also serves as the Supreme
Being's name. Of course a feminine noun can be
formed from bóg; it's bogini 'goddess' -- a
common noun, not a name.
A related question is how Polish
handles the concept of 'female Christian priest' (as you have in the Church
of England). 'Priestess', I think, is unthinkable.
Mark.