ant·ac·id (ānt-ās'ĭd) adj. Counteracting or neutralizing acidity, especially of the stomach. n. A substance, such as magnesia or sodium bicarbonate, that neutralizes acid.
antacid ant·ac·id (ānt-ās'ĭd) or an·ti·ac·id (ān'tē-ās'ĭd, ān'tī-) adj. Counteracting or neutralizing acidity, especially of the stomach. n. A substance, such as sodium bicarbonate, that neutralizes acid.