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

The purple shampoo is enriched with hydrolyzed vegetable protein, which has amino acids that penetrate the hair shafts to improve elasticity and prevent breakage. —Jenny Berg, Allure, 31 Dec. 2024

These foods contain amino acids that turn on muscle protein synthesis. —Audrey Noble, Vogue, 30 Dec. 2024

Its intensely moisturizing formula features amino acids that make up the protein keratin (which is key for maintaining your hair’s structure and strength) and hair-softening plant extracts. —Sara Coughlin, SELF, 23 Dec. 2024

The Murchison meteorite, which fell in Australia in 1969, contains more than 96 different amino acids. —Elise Cutts, WIRED, 22 Dec. 2024

Word History

First Known Use

1897, in the meaning defined above

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