vitamin A aldehyde

from The Collaborative International Dictionary of English v.0.48

Retinal \Ret"i*nal\, n. (Chem.)
   A retinoid compound ({C20H28O}), closely related to vitamin
   A, which is a component of the visual pigments in the eye. It
   is also called {retinaldehyde} and {vitamin A aldehyde}.
   [PJC]