The Collaborative International Dictionary of English v.0.48:

Sunglass \Sun"glass`\, n.; pl. Sunglasses.
   A convex lens of glass for producing heat by converging the
   sun's rays into a focus. "Lighting a cigar with a sunglass."
   --Hawthorne.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sunglasses
    n 1: spectacles that are darkened or polarized to protect the
         eyes from the glare of the sun; "he was wearing a pair of
         mirrored shades" [syn: sunglasses, dark glasses,
         shades]

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "sunglasses":
   Polaroid glasses, bifocals, blinkers, cheaters, colored glasses,
   contact lens, dark glasses, divided spectacles, eyeglass,
   eyeglasses, eyeshade, eyeshield, glasses, goggles, granny glasses,
   harlequin glasses, horn-rimmed glasses, lorgnette, lorgnon,
   mini-specs, monocle, nippers, pair of glasses, peepers,
   quizzing glass, readers, reading glasses, shades, smoked glasses,
   specs, spectacles, sun-specs, trifocals, visor