Gei ‧ ger count ‧ er /ˈɡaɪɡə ˌkaʊntə $ -ɡər ˌkaʊntər/ BrE AmE noun [countable]
[ Date: 1900-2000 ; Origin: Hans W. Geiger (1882-1945), German scientist who invented it (with Walter M. Müller) ]
an instrument that finds and measures ↑ radioactivity
Gei ‧ ger count ‧ er /ˈɡaɪɡə ˌkaʊntə $ -ɡər ˌkaʊntər/ BrE AmE noun [countable]
[ Date: 1900-2000 ; Origin: Hans W. Geiger (1882-1945), German scientist who invented it (with Walter M. Müller) ]
an instrument that finds and measures ↑ radioactivity
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012