/ bɜːˈkiːliəm; ˈbɜːkliəm; NAmE ˈbɜːrkliəm/ noun
[ U ] ( symb Bk ) a chemical element. Berkelium is a radioactive metal that is produced artificially from americium and helium .
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WORD ORIGIN
1949: from Berkeley , a city in western California, USA (where it was first made) + -ium .