Etymology From sun + glass, as a back-formation when referring to sunglasses.
1
Attributive form of sunglasses, used chiefly in phrases.
a sunglass holder
They trekked through Europe, discovering designers like Melinda Gloss and the Italian sunglass manufacturer LGR, with whom they secured exclusive United States representation.2009 January 8, Mike Albo, “Of-the-Moment, Yet So Five Months Ago”, in New York Times:
sunglass
noun
Etymology From sun + glass, as a back-formation when referring to sunglasses.
1
Archaic A convex lens of glass for producing heat by converging the sun's rays into a focus.
Lighting a cigar with a sunglass1837 March 6, Nathaniel Hawthorne, “(please specify the chapter or story)”, in Twice-Told Tales, Boston, Mass.: American Stationers Co.; John B. Russell, →OCLC: