Semantics

belly
У тебя живот не влезает в брюки. Your belly's hanging over the top of those pants.
stomach
Ой, какой у тебя огромный живот! Наверно, двойня будет! Oh, what an enormous stomach! I'll bet you're going to have twins!
abdomen
— Положите грелку на живот. "Put a hot water bottle on your abdomen."
This entry is concerned with the use of the word живот to refer to the external part of the body of a human or animal that extends from the lower ribs to the pelvis, and also to the cavity in this part of the body. For animals this meaning can also be rendered by the word брюхо.