Definitions:
a unit of radioactivity, corresponding to 3.7 × 10¹⁰ disintegrations per second.

marie (1867–1934), polish-born french physicist, and pierre (1859–1906), french physicist, pioneers of radioactivity. working together on the mineral pitchblende, they discovered the elements polonium and radium, for which they shared the 1903 nobel prize for physics with becquerel. after her husband's accidental death marie received another nobel prize (for chemistry) in 1911 for her isolation of radium. she died of leukaemia, caused by prolonged exposure to radioactive materials.