magnifying glass

magnifying glass (plural magnifying glasses)

1. An instrument made of convex glass, used to magnify.
   • 2013 September-October, Henry Petroski, “The Evolution of Eyeglasses”, in American Scientist:

     The ability of a segment of a glass sphere to magnify whatever is placed before it was known around the year 1000, when the spherical segment was called a reading stone, essentially what today we might term a frameless magnifying glass or plain glass paperweight.

• loupe