sunglassEtymologyFrom sun + glass, as a back-formation when referring to sunglasses.sunglass means A convex lens of glass for producing heat by converging the sun's rays into a focus. Lexicurio rates it Sui generis — a strength score of 88 out of 100.nounA convex lens of glass for producing heat by converging the sun's rays into a focus.“Lighting a cigar with a sunglass”