Geiger counter
noun
Gei·ger counter ˈgī-gər- 
: an instrument for detecting the presence and intensity of radiations (such as cosmic rays or particles from a radioactive substance) by means of their ionizing effect on an enclosed gas which results in a pulse that is amplified and fed to a device giving a visible or audible indication
Word History
Etymology
Hans Geiger †1945 German physicist
First Known Use
1924, in the meaning defined above
Kids Definition
Geiger counter
noun
Gei·ger counter ˈgī-gər-
: an instrument for detecting the presence of cosmic rays or radioactive substances
Medical Definition
Geiger counter
noun
Gei·ger count·er ˈgī-gər-ˌkau̇n-tər
: an instrument for detecting the presence and intensity of radiations (as cosmic rays or particles from a radioactive substance) by means of the ionizing effect on an enclosed gas which results in a pulse that is amplified and fed to a device giving a visible or audible indication