strobe light /ˈstrəʊb ˌlaɪt $ ˈstroʊb-/ BrE AmE ( also strobe ) noun [countable]
[ Date: 1900-2000 ; Origin: stroboscope 'instrument producing quickly flashing light' (19-21 centuries) , from Greek strobos 'going around quickly' + English -scope (as in telescope ) ]
a light that flashes on and off very quickly, often used in places where you can dance