What term is used to refer to the navel in slang?

The term "umbilicus" refers to the navel, which is the small scar on the abdomen that marks the spot where the umbilical cord was attached during fetal development. The umbilicus is a standard anatomical term used in both medical and lay contexts, though it may not commonly be recognized in everyday conversation as a slang term.

The other terms provided have different meanings and contexts. "Stomach" generally refers to the organ that is part of the digestive system and not specifically the navel. "Abdomen" denotes the area of the body that contains several digestive organs, and while it includes the navel, it is not a slang term for it. "Waist" refers to the part of the body between the ribs and hips, which is also not synonymous with the navel. Thus, umbilicus is the most accurate term for the navel in this context.