vitamin A

noun

: any of several fat-soluble vitamins (such as retinol) that are found especially in green or orange vegetables (such as carrots or spinach) and in animal products (such as egg yolk, butter, or liver) and whose deficiency in the animal body causes epithelial tissues to become keratinous (as in the eye with resulting visual defects)

Examples of vitamin A in a Sentence

Recent Examples on the Web

Providing vitamin A supplementation and, on a larger scale, ensuring adequate nutrition overall, decreases the risk of death from measles and many other infections. —Madhukar Pai, Forbes, 23 Jan. 2025

Pregnant adults should limit vitamin A intake to 3,000 micrograms (mcg) daily.7 Risks for people with chronic kidney or liver disease: People with chronic kidney or liver disease should avoid multivitamins without consulting a healthcare provider. —Lindsay Curtis, Verywell Health, 22 Jan. 2025

Retinol is a vitamin A derivative and only one of several types of retinoids. —Sarah Han, Allure, 7 Jan. 2025

Daniel Isaacs, the brand’s chief product officer and director of research, previously told Vogue that the cream was formulated with vitamin A sensitivity in mind. —Jenny Berg, Vogue, 5 Jan. 2025

Word History

First Known Use

circa 1920, in the meaning defined above

Kids Definition

vitamin A

noun

: any of several vitamins or a mixture of them that are found especially in green and orange vegetables (as carrots or spinach) and animal products (as egg yolk, butter, or liver) and are needed especially for good vision

Medical Definition

vitamin A

noun

: any of several fat-soluble vitamins or a mixture of two or more of them whose lack in the animal body causes keratinization of epithelial tissues (as in the eye with resulting night blindness and xerophthalmia): as

a

: a pale yellow crystalline highly unsaturated alicyclic alcohol C₂₀H₂₉OH that is found in animal products (as egg yolk, milk, and butter) and especially in marine fish-liver oils (as of cod, halibut, and shark) and that is used in various forms in medicine and nutrition

called also retinol, vitamin A₁

b

: a yellow viscous liquid alicyclic alcohol C₂₀H₂₇OH that contains one more double bond in a molecule than vitamin A₁ and is less active biologically in mammals and that occurs especially in the liver oil of freshwater fish

called also vitamin A₂