Bread is a staple food made primarily by baking flour and a leavening agent, such as yeast. It is often shaped into loaves or buns before baking.
The occupants of the RIS Bouteina ate half the bread supply of Starbase 47 (Lyran) in two weeks, after they had to stay at the starbase, awaiting repairs. Brianna Reiss' first flight as a pilot was to resupply Starbase 47 in flour so that the Romulans keep eating bread. As vegetarians, Vulcans were also very fond of bread. Also, Lyrans preferred eating meat to bread. (RIS Bouteina: "Broken Bread")