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

Instead of using amino acids—found in other animal opsins—ASO-II opsins employ chloride ions. —Maria Mocerino, Interesting Engineering, 7 Sep. 2025

The compound is made from three amino acids that serve as a source of energy for your muscles. —Brittney Melton, NPR, 5 Sep. 2025

The new formula also includes L-theanine, a non-protein amino acid primarily found in green and black tea and some mushrooms, Healthline states. —Greta Cross, USA Today, 5 Sep. 2025

Matcha is a powdered form of green tea with a smooth, earthy flavor and a more sustained energy release thanks to L-theanine, an amino acid. —Lauren Panoff, Verywell Health, 4 Sep. 2025

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