Longman Dictionary English From Longman Dictionary of Contemporary EnglishRelated topics: Compounds, FoodMSGMSG /ˌem es ˈdʒiː/ noun 1 [uncountable]HCCDF (monosodium glutamate) a chemical that is added to food to make it taste better2 [countable] (also msg) (message) used especially in text messages sent or received on a mobile phone ldoceonline.com