Take this medication 'on an empty stomach'. [=when your stomach is empty because you have not eaten for a time]
When I had the flu, just the thought of eating made me 'sick to my stomach'. [='nauseous']
She felt a flutter in 'the pit of her stomach' when he walked through the door.
(..) Shut down till midday. And I had a vision. Yes, last night, I had a vision and I felt God's breath move through me. And it rolled down into my stomach. It sloshed around. And my stomach spoke in a whisper, not a shout, "Touch this woman with your hands and caress her." Yes. (..)2007 There Will Be Blood