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 concealer also has a blend of amino acids and a proprietary hibiscus complex that repair skin damage, lock in moisture, and brighten, leaving a soft, radiant glow. —Alyssa Morin, InStyle, 3 Jan. 2026

Instead of sitting on top of the hair, the formula uses bio-protein care and glutamic amino serum to feed the fiber with usable amino acids that help refill structural gaps, while ceramides and conditioning agents smooth the cuticle so strands bend without snapping. —Jailynn Taylor, Allure, 31 Dec. 2025

These amino acids may protect against the development of atherosclerosis, or the thickening or hardening of the arteries caused by a buildup of plaque. —Jillian Kubala, Health, 31 Dec. 2025

When a mouse is recovering from an infection, cells in the gut can sense certain amino acids and reduce the animal’s appetite. —The New York Times News Service Syndicate, San Diego Union-Tribune, 30 Dec. 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