In most dialects, primarily refers to the bellybutton or navel. Pronunciation may vary.
In Mesa Grande, millyepuu is "umbilical cord" while milyepuu (the "small" version of the former) is "navel/belly button". Other dialects may use pehaa "guts, intestines" to refer to the umbilical cord.
May also be used to mean "spark plug" of a car.