vitamin a defined in 1951 yearvitamin a - vitamin a;
vitamin a - Required by man and other vertebrates but not by other organisms. Fat soluble. Stored in liver. Deficiency in man causes night-blindness (the vitamin being a constituent of visual purple) and keratinization of cornea, and other effects involving epidermis and nervous tissue. Carotene which is synthesized by green plants, and some related pigments, can be converted by animals to Vitamin A, and the vertebrates obtain their supply of the vitamin ultimately from this source.
near vitamin a in Knolik
definition of word "vitamin a" was readed 1295 times