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

Another notable dual winner was Frederick Sanger, who won in 1958 for sequencing the amino acids that make up insulin, and again in 1980 for developing a method to sequence strands DNA. — Adam Kovac, Scientific American, 7 Oct. 2026

The homochirality of biomolecules such as sugars and amino acids—the building blocks of living systems—is essential to many fundamental biological processes and the effectiveness of pharmaceutical drugs. — Encyclopedia Britannica, 7 Oct. 2026

Four types of hyaluronic acid plump skin and counteract potential dryness, while collagen amino acids and antioxidants help protect skin’s natural collagen for a firmer, smoother look. — Christa Joanna Lee, Allure, 7 Oct. 2026

Like hands, all amino acids exist as two mirrored variants, but only one of them is found in the proteins in your cells. — Prabhat Ranjan Mishra, Interesting Engineering, 7 Oct. 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