retinal purple(n = noun.substance) rhodopsin, visual purple - a red photopigment in the retinal rods of vertebrates; dissociates into retinene by light;
is a kind of photopigment
is a part of retinal rod, rod, rod cell

banded purple, early purple orchid, late purple aster, order of the purple heart, purple, purple amaranth, purple anise, purple apricot, purple avens, purple bacteria, purple beech, purple boneset, purple chinese houses, purple clematis, purple clover, purple cress, purple emperor, purple finch, purple fringeless orchid, purple fringeless orchis, purple gallinule, purple grackle, purple granadillo, purple ground cherry, purple heart, purple heather, purple loco, purple locoweed, purple loosestrife, purple martin, purple milk vetch, purple mullein, purple nightshade, purple onion, purple orchis, purple osier, purple passage, purple pea, purple poppy mallow, purple rock brake, purple sage, purple sanicle, purple saxifrage, purple silkweed, purple strawberry guava, purple trillium, purple velvet plant, purple virgin's bower, purple willow, red-spotted purple, reddish purple, retinal, retinal cone, retinal detachment, retinal rod, retinal scanning, royal purple, texas purple spike, tyrian purple, visual purple