isonephEtymologyFrom iso- + Ancient Greek νέφος (néphos, “cloud”) (see nepho-).isoneph means an isoline indicating equal cloud cover. Lexicurio rates it Sui generis — a strength score of 87 out of 100.nounAn isoline indicating equal cloud cover.“After plotting the amounts in oktas, isonephs were drawn at two-okta intervals. Closely spaced isonephs indicate a sharp edge to a cloud sheet, the edge approximately coinciding with the four-okta isoneph. A station reporting four oktas and lying in a region of close isonephs would have one side of its sky relatively cloudfree and the opposite side covered.”