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

Glycine is an amino acid which serves functions in many areas of the human body such as a neurotransmitter, a component in collagen, and a building block for other important molecules in the body. —Elsa Ohlen, CNBC, 9 June 2026

Creatine Side Effects Creatine is an amino acid produced by the body. —Patty Weasler, Verywell Health, 9 June 2026

Composed of glucose and an amino acid called glutamine, these molecules are used by the body to build new cells. —Ramon Sun, The Conversation, 9 June 2026

Bond-building hair products—which work by repairing the amino acid bonds that give hair its strength and structure—have surged in popularity in recent years. —Conçetta Ciarlo, Vogue, 8 June 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