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

Protein Supports Concentration Your brain relies on a steady supply of amino acids, small compounds that are the building blocks of protein, to produce neurotransmitters. —Kristen Gasnick, Verywell Health, 21 Apr. 2026

It’s made with glycerin and amino acids and acts as a very gentle cleanser. —Bestreviews, Mercury News, 16 Apr. 2026

Peptides are short chains of amino acids — think of them as small building blocks of proteins — that are being explored for a wide range of health and wellness uses. —Brandon Gomez, CNBC, 16 Apr. 2026

The change allows compounding pharmacies to produce the peptides — a broad category of amino acids — while the Food and Drug Administration is still evaluating their safety and effectiveness. —Aria Bendix, NBC news, 16 Apr. 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