vitamin A

American  

noun

1. a yellow, fat-soluble, solid terpene alcohol, C 20 H 30 O, obtained from carotene and occurring in green and yellow vegetables, egg yolk, etc.: essential to growth, the protection of epithelial tissue, and the prevention of night blindness.

---

vitamin A British  

noun

1. Also called: vitamin A1.   retinol.  a fat-soluble yellow unsaturated alcohol occurring in green and yellow vegetables (esp carrots), butter, egg yolk, and fish-liver oil (esp halibut oil). It is essential for the prevention of night blindness and the protection of epithelial tissue. Formula: C 20 H 30 O

---

vitamin A Scientific  

1. A fat-soluble vitamin important for normal vision, tissue growth, and healthy skin. It is found in fish-liver oils, milk, green leafy vegetables, and red, orange, and yellow vegetables and fruits. A deficiency of vitamin A in humans causes poor vision at night and damage to the skin and mucous membranes. Also called retinol. Chemical formula: C ₂₀ H ₃₀ O.

---

Etymology

Origin of vitamin A

First recorded in 1920–25

Example Sentences

See Examples For:

vitamin A

Those which are particularly toxic to the liver when taken in high doses include vitamin A, glutamine, ashwagandha and green tea extract.

From BBC ● Jun. 20, 2026

“Inadequate nutrition, particularly vitamin A deficiency, can impair the lining of the digestive tract, predisposing birds to inflammation and secondary illness.”

From Los Angeles Times ● Apr. 20, 2026

The mutation appears to enhance the activity of enzymes that convert vitamin A into its active forms.

From Science Daily ● Apr. 15, 2026

Taking too much vitamin A can cause health problems, including birth defects if taken while pregnant.

From Salon ● Mar. 19, 2026

Most of the nuts are especially noteworthy in high vitamin A and B1 content.

From Northern Nut Growers Association Report of the Proceedings at the 41st Annual Meeting Pleasant Valley, New York, August 28, 29 and 30, 1950 by Northern Nut Growers Association