Definition of "magnesia" [mag•ne•si•a]

• Magnesium oxide. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "MacNeil was using milk of magnesia, which is the hydroxide, for 'gastric acidity'."
• "Magnesium oxide, sometimes called magnesia or magnesia usta, resembles lime in many respects."
• "It is then gradually removed one shelf lower as the decomposition increases, until it arrives at the bottom shelf, where it is completely decomposed in the state of magnesia, which is emptied through, E."