| any of various powders used as a substitute for yeast in baking, composed of sodium bicarbonate mixed with an acid substance, as cream of tartar, capable of setting carbon dioxide free when the mixture is moistened, causing the dough to rise. |
| bak·ing powder (bā'kĭng) n. A mixture of baking soda, starch, and at least one slightly acidic compound such as cream of tartar that works as a leavening agent in baking by releasing carbon dioxide when mixed with a liquid, such as milk or water. |
baking powder  (bā'kĭng) Pronunciation Key
A mixture of baking soda, a nonreactive filler (such as starch), and at least one slightly acidic compound (such as cream of tartar). Baking powder works as a leavening agent in baking by releasing carbon dioxide when mixed with a liquid, such as milk or water. |