1843, "pertaining to light;" 1899, "pertaining to the parts of the ocean penetrated by sunlight," from Greek phot-, comb. form of Greek phos "light" (related to phainein "to show, to bring to light;" see phantasm) + -ic.
Relating to the layer of a body of water that is penetrated by sufficient sunlight for photosynthesis. The depth of the photic zone is dependent on the clarity of the water and the amount and intensity of direct sunlight, although it does not usually exceed 200 m. Also called euphotic. Compare aphotic.