"Air sac" and "air cell" in a chicken embryo
According to Atlas of Chick Development by Ruth Bellairs and Mark Osmond, a book I'm using for my developmental biology course :


  Air space  is the space between the two shell membranes at the blunt end of the egg. The chick pushes its beak into this space shortly before hatching and takes its first breathe of air.


Besides allantois is the extra embryonic membrane and the space enclosed by it is allantoic cavity.

Here label 2 is Allantoic cavity.