noun, plural un·der·bel·lies.
Examples from the Web for underbelly
The press was at the height of its power when the Monica story began and Drudge was its underbelly.
Come to think of it, the underbelly of Clinton & Co. has been on display all summer.The Clintons Can’t Shake Their Reputation for Ethical Shadiness|Lloyd Green|September 19, 2013|DAILY BEAST
Goode was peering at the ivory inlay on the underbelly of the stock.Murder in the Gunroom|Henry Beam Piper
The scout ship responded like a nervous horse and fluttered away as the rocket burned and arced beneath the underbelly.The Sex Life of the Gods|Michael Knerr