It means central part, nucleus. Central, Center, Middle, Middle Area. A scar left by the cutting of the umbilical cord on every viviparous being at birth in the middle of the womb.
1º_ Scar on the abdomen of viviparous animals that remains after the umbilical cord has dried. Because of its position (masomenos) in the middle of the human body, it is a derogatory way of calling the center of something.