1. A detector of radio waves used in very early radio receivers

1. any device in which an imperfectly conducting contact between pieces of metal or other conductors loosely resting against each other is materially improved in conductivity by the influence of hertzian waves; -- so called by sir O. J. lodge in 1894 on the assumption that the impact of the electic waves caused the loosely connected parts to cohere, or weld together, a condition easily destroyed by tapping. A common form of coherer as used in wireless telegraphy consists of a tube containing filings (usually a pinch of nickel and silver filings in equal parts) between terminal wires or plugs (called conductor plugs).

1. in electricity, a tube filled with a conducting substance in powdered or granular form, as metal filings, which, when struck by an electric wave, as that sent out from a wireless telegraph station, decreases in electrical resistance, probably by the particles making a better contact with each other, and so is used to discover very minute electric waves, as in wireless telegraphy. after the passing of the electric wave the resistance of the coherer usually remains low, but it rises again when the tube is tapped.