1) Pigment 2) Retinal 
Synonym for retinaldehyde ... <chemical> A carotenoid constituent of visual pigments. It is the oxidised form of retinol which functions as the active component of the visual cycle. ... It is bound to the protein opsin forming the complex rhodopsin. When stimulated by visible light, the retinal component of the rhodopsin complex undergoes iso...
Type: Term Pronunciation: ret′i-nēn Synonyms: retinaldehyde
[n] - either of two yellow to red retinal pigments formed from Rhodopsin by the action of light
retinal noun either of two yellow to red retinal pigments formed from rhodopsin by the action of light