ret·i·no·ic acid (rět'n-ō'ĭk) n.
In both senses also called tretinoin, vitamin A acid.
A vitamin A derivative, C20H28O2, that is a regulator substance in morphogenesis and functions in the growth and development of bone and the maintenance of epithelium.
A preparation of this, used topically to treat acne and to modify the appearance of fine wrinkles, hyperpigmentation, and roughness of facial skin.
(rět'n-ō'ĭk) 