1) Iodopsin 1) Pigment 
Photopigments are unstable pigments that undergo a chemical change when they absorb light. The term is generally applied to the non-protein chromophore moiety of photosensitive chromoproteins, such as the pigments involved in photosynthesis and photoreception. In medical terminology, `photopigment` commonly refers to the photoreceptor proteins o.....
<plant biology> Pigment involved in photosynthesis in plants. Includes chlorophyll, carotenoids and phycobilins. ... (31 Dec 1997) ... 
Pigment involved in photosynthesis in plants. Includes chlorophyll, carotenoids and phycobilins.
[n] - a special pigment found in the rods and cones of the retina
photopigment 1. A pigment, such as a retinal pigment, that is unstable in the presence of light. 2. Pigment involved in photosynthesis in plants which includes chlorophyll, carotenoids, and phycobilins.
noun a special pigment found in the rods and cones of the retina