The American Heritage® Dictionary of the English Language, 4th Edition
n. An instrument used to detect the presence, sign, and in some configurations the magnitude of an electric charge by the mutual attraction or repulsion of metal foils or pith balls.
n. a simple device that detects the presence of an electric charge by the mutual repulsion of metal foils or pith balls
the GNU version of the Collaborative International Dictionary of English
n. An instrument for detecting the presence of electricity, or changes in the electric state of bodies, or the species of electricity present, as by means of pith balls, and the like.
The Century Dictionary and Cyclopedia
n. An instrument for observing or detecting the existence of free electricity, and, in general, for determining its kind.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. measuring instrument that detects electric charge; two gold leaves diverge owing to repulsion of charges with like sign
Word Usage
"By the side of gold leaf electroscopes we see a feather electroscope, which is fastened to its support by means of a silken thread."