Umbilingus 

Oral sex of the belly button.

My girlfriend was performing umbilingus but she stopped when she got a piece of lint in her mouth.

Umbilingus by DRDMH May 1, 2010

umbilicus

Where the umbilical cord was cut, and the stump dries up and falls off, leaving an indentation in the middle of your abdomen...A belly button or navel. Something that kept you alive, but most commonly it gets cut and separates you from your Mother and you at birth...if it doesn't get cut then you don't learn to be accountable; and men especially, could suffer separation anxiety from their mothers and have a hard time with all future relationships. It gets tied off and heals up well and is often labeled either an "innie" or an "outie". Pretty cute when girls pierce them, boys sometimes get lint in theirs. A place to store your bubble-gum for later. It's a nice way to fall asleep, with your finger in your bellybutton. It can be pronounced UM BILLY KISSor UM BIL LIKE US....

My tummy is sore....No, maybe it's my tummy button more in the central part of my lower abdomen, just about two fingers to the right of my umbilicus. The newborn baby has had his cord clamp removed, and the skin is slightly moist, so to properly heal up and dry out, we keep the diaper folded down below the level of the infants' umbilicus.

umbilicus by Judy.groovy July 24, 2016

Coitus umbilicus 

The act of engaging in intercourse, to climax or not, with the umbilicus/navel/belly button. It frequently occurs in inexperienced males that are seeking any dark crevice for sexual pleasure while lacking in knowledge of the female anatomy. It can also be intentional, especially when the sexual act involves a partner, male or female, with a significant amount soft tissue is present in the neighboring structures. It is not to be confused with coitus panniculus, engaging in coitus with the folds of abdominal fat.

I was unaware of the female anatomy my first sexual interaction. While searching for home, I engaged in coitus umbilicus as she writhed from pain as her happy trail was mechanically stripped of hair from the friction.

Coitus umbilicus by William Black August 26, 2013