High quality, premium, superior, excellent, outstanding are some of the antonyms for the word "low grade." An antonym is a word that has an opposite meaning to another word. In the context of education, low grade refers to a mark or score that indicates a poor performance. Therefore, its antonyms signify a better or excellent performance. In the healthcare industry, low-grade refers to a mild form of a disease or infection, and the antonyms imply a severe or critical illness. Similarly, in the context of industry and manufacturing, low-grade denotes products that are of poor quality, while its antonyms indicate top-notch, valuable, and superior items.