n. 凸透镜, 太阳眼镜

[ noun ]
a convex lens that focuses the rays of the sun; used to start a fire
<noun.artifact>

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.