The Bridge
This is the depth between a girl's bikini bottom and her skin, as it spans the distance between her hip bone over to her tummy. This phenomena most likely occurs when a girl is laid flat out on her back.
The Nelaton's Line (also known as the Roser-Nelaton line) is a theoretical line, drawn from the anterior superior iliac spine of the female to her tuberosity of the ischium. Also see The Gap and The Valley to learn about other exciting female anatomy.
Example:
"Dude, did you see how deep the bridge was on that chick???!!!"
"Yes dude, I would like to camp out under it tonight and look at the stars"
"Dude, did you see how deep the bridge was on that chick???!!!"
"Yes dude, I would like to camp out under it tonight and look at the stars"