Definitions

1. noun

the part of something (such as a city or an organization) that is not publicly visible or openly acknowledged, especially its most disreputable or corrupt aspect

“The underbelly of the city’s glamour is its high rate of crime.”

2. noun

the bottom or underside of something

“The underbelly of the boat was damaged in the storm.”

3. verb

to attack or criticize someone or something from the underside or in a hidden way

“The politician was accused of trying to underbelly her opponent’s character.”