/uy'euh dop"sin/ , n. Biochem.
a photosensitive violet pigment that occurs in the cones of the retina and is transformed by light into retinal and an opsin protein. Cf. rhodopsin .
[ 1935-40; iód ( es ) taken as deriv. of íon violet (see IODINE) + OPSIN, on the pattern of RHODOPSIN ]