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 keratin and silk amino acids help keep hair soft and smooth while the dye works, so your finished color looks multidimensional instead of flat. —Taryn Brooke, Glamour, 21 Nov. 2025

Its Hadasei-3—a blend of superfoods, amino acids, and AHAs—powers each of its formulas. —Kiana Murden, Vogue, 17 Nov. 2025

Undigested protein or the breakdown of certain amino acids can cause gut bacteria to produce harmful metabolites, such as ammonia and hydrogen sulfide. —Joy Emeh, Health, 14 Nov. 2025

Some medical studies have found taurine, an amino acid, to help with athletic performance, heart health and exercise recovery. —Hannah Yasharoff, USA Today, 12 Nov. 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