Definition of "flatten out" [flatten out]

• Become flat or flatter (verb)

WordNet. Princeton University. 2010.

• "But things had begun to flatten out a bit, and Highway 50, the winding two-lane highway we’d been on since leaving Yosemite changed to four-lanes, with two going each way."
• "The Aerospatiale engine overhead shrieked to life, and the Dolphin's sagging thirty-nine-foot rotors began to flatten out into a silver blur."