amino acid

noun

: an amphoteric organic acid containing the amino group NH₂

especially : any of the various amino acids having the amino group in the alpha position that are the chief components of proteins and are synthesized by living cells or are obtained as essential components of the diet

Examples of amino acid in a Sentence

Recent Examples on the Web

Ingredients like apple stem cells help support the hair’s natural growth cycle, and its amino acid complex strengthens hair fibers. — Amanda Le, InStyle, 5 Nov. 2026

Arginine is an amino acid that the body needs to make nitric oxide, a compound that relaxes and expands blood vessels, improving blood flow. — Mark Gurarie, HEALTH, 4 Nov. 2026

Over that period, the Maillard reaction causes sugars and amino acids to react under heat, which gradually turns the cloves dark. — Ryan Brennan, Kansas City Star, 3 Nov. 2026

The legume provides a complex array of proteins in animal feed that other food sources and synthetic amino acids cannot replicate. — Joel Wuthnow, Foreign Affairs, 2 Nov. 2026

Word History

First Known Use

1897, in the meaning defined above

Rhymes for amino acid

• antacid
• placid

Kids Definition

amino acid

noun

ami·​no acid

ə-ˈmē-nō-

: any of numerous acids that include some which are the building blocks of proteins and are made by living cells from simpler compounds or are obtained in the diet

Medical Definition

amino acid

noun

: an amphoteric organic acid containing the amino group NH₂

especially : alpha-amino acid