monosodium glutamate

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A white crystalline compound, C₅H₈NO ₄Na, a monobasic salt of glutamic acid, used as a flavor enhancer in foods.

from the GNU version of the Collaborative International Dictionary of English.

• noun The monosodium salt of the natural amino acid L-glutamine (C5H8NNaO4), used as a food additive to enhance flavor; abbreviated MSG. It is usually marketed as the monhydrate (C5H8NNaO4.H2O). It is commmonly used in Chinese-American restaurants, and has been identified as a main cause of Chinese restaurant syndrome.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun chemistry The mono sodium salt of the amino acid, glutamic acid; present in soy sauce; used as a condiment in Chinese and Japanese cooking, and as a food additive to enhance flavor and add the umami taste. Abbreviations: MSG, E621.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun white crystalline compound used as a food additive to enhance flavor; often used in Chinese cooking