The Collaborative International Dictionary of English v.0.48:

Microscope \Mi"cro*scope\, n. [Micro- + -scope.]
   An optical instrument, consisting of a lens, or combination
   of lenses, for making an enlarged image of an object which is
   too minute to be viewed by the naked eye.
   [1913 Webster]

   Compound microscope, an instrument consisting of a
      combination of lenses such that the image formed by the
      lens or set of lenses nearest the object (called the
      objective) is magnified by another lens called the ocular
      or eyepiece.

   Oxyhydrogen microscope, and Solar microscope. See under
      Oxyhydrogen, and Solar.

   Simple microscope, or Single microscope, a single convex
      lens used to magnify objects placed in its focus.
      [1913 Webster]

WordNet (r) 3.0 (2006):

simple microscope
    n 1: light microscope consisting of a single convex lens that is
         used to produce an enlarged image; "the magnifying glass
         was invented by Roger Bacon in 1250" [syn: hand glass,
         simple microscope, magnifying glass]