essential amino acid

noun

: any of various amino acids that are required for normal health and growth in many vertebrates, are either not manufactured in the body or manufactured in insufficient quantities, are usually supplied by dietary protein, and include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine compare nonessential amino acid

Examples of essential amino acid in a Sentence

Recent Examples on the Web

Researchers highlighted three essential amino acids that are building blocks of protein — methionine, isoleucine and valine. — Khloe Quill, FOXNews.com, 3 Aug. 2026

Of the nine essential amino acids that people and many mammals need to survive, studies suggest that restricting some of them could extend lifespan, the review says. — Dominique Mosbergen, Time, 3 Aug. 2026

Dietary protein is our main source of essential amino acids because our bodies can’t make these molecules on their own. — Adam Kovac, Scientific American, 31 July 2026

Milk provides high-quality protein, including whey and casein, which contain all nine essential amino acids. — Trista Chan, Health, 19 July 2026

Word History

First Known Use

1911, in the meaning defined above

Rhymes for essential amino acid

• antacid
• placid

Kids Definition

essential amino acid

noun

: an amino acid that is necessary for proper growth of the animal body and that cannot be made by the body in sufficient amounts but must be obtained from food containing proteins

Medical Definition

essential amino acid

noun

: any of various alpha-amino acids that are required for normal health and growth, are either not manufactured in the body or manufactured in insufficient quantities, are usually supplied by dietary protein, and in humans include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine