Nadir and Underbelly

Nadir noun - The lowest point or level.

Underbelly and nadir are semantically related In some cases you can use "Underbelly" instead a noun "Nadir".

Underbelly noun - A social sphere that exists outside of the mainstream.

Nadir and underbelly are semantically related in bottom topic. Sometimes you can use "Nadir" instead a noun "Underbelly", if it concerns topics such as foundation.