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

Kennedy, a vaccine skeptic, has also supported the use of vitamin A under the supervision of a physician to treat people with measles, creating concerns among health experts who have cautioned about the vitamin’s effectiveness. —Antonio Pequeño Iv, Forbes.com, 20 May 2025

Other sources of vitamin A include sweet potatoes, milk, cantaloupe, ricotta cheese, eggs, and salmon. —Karla Walsh, Better Homes & Gardens, 18 May 2025

This is a pure vitamin A ingredient that increases cell turnover, which can help reduce the appearance of wrinkles and lead to an anti-aging effect.5 Retinoids usually refer to prescription medications available through a healthcare provider. —Sarah Bence, Verywell Health, 15 May 2025

Experts have warned that high doses of vitamin A, often found in cod liver oil, can be harmful, especially to young children. —Amanda Castro, MSNBC Newsweek, 14 May 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