In anatomy, the stomach or belly was an organ located in the abdomen that was used to digest food.
Ferengi Rule of Acquisition No. 214 stated, "Never begin a negotiation on an empty stomach." (DS9: "The Maquis, Part I")
The Novan expression for having an empty stomach was "a hollow belly". (ENT: "Terra Nova")
The Vok'sha from Rakella Prime believed that hate was a beast living inside the stomach. Their greatest mythical hero was a man who ate stones for twenty-three days to kill the beast, and became a saint. (VOY: "Heroes and Demons")
Lurians had two stomachs. They could use their second stomach to store liquids for several years. (DS9: "Who Mourns for Morn?")
Takarans had twin stomachs located in the epigastric. (TNG: "Suspicions")
On Earth, a tradition to get good luck was to pat the belly of Buddha. (ENT: "The Andorian Incident")
In 2151, Porthos came down with a little gastrointestinal distress, because Captain Archer had fed him cheese again. Doctor Phlox advised the captain not to feed any more dairy products to Porthos. (ENT: "Dear Doctor")
In a line from the final draft script of "Broken Bow", Archer claimed that "a starship runs on its stomach."
In 2286, Montgomery Scott developed a case of "sour stomach" after eating Klingon food packs. (Star Trek IV: The Voyage Home)
In 2367, while rehearsing A Christmas Carol, Lieutenant Commander Data, playing the role of Ebenezer Scrooge, stated to Jacob Marley's ghost that he didn't believe in him, that he doubted his senses because "a slight disorder of the stomach makes them cheats." (TNG: "Devil's Due")
When Lwaxana Troi was attracted to Odo in 2369, he attempted to discourage her interest by stating he couldn't eat as he did not have a stomach. (DS9: "The Forsaken")
According to Benjamin Sisko in 2372, his father always said, "The way to a woman's heart is through her stomach." (DS9: "The Way of the Warrior")
Klingons had, among other things, a redundant stomach. Tom Paris believed this meant that Klingons were incapable of getting nauseated and was thus surprised when B'Elanna Torres stated how ill she felt in 2373. (VOY: "Macrocosm")
In the first draft script of ENT: "Fusion" (which had the working title "Equilibrium"), Trip Tucker and his brother were referred to, in Trip's dialogue, as having required, one Halloween during their childhood, to have their stomachs pumped at a hospital because they had eaten too much candy after going trick or treating.