Although the word is rendered in Chinese characters in several versions, such as "婆娑羅", and "vajra" in Sanskrit refers to diamond, it is not known as to how the meaning of the word was transformed as it was used in medieval Japan.
婆娑羅など幾つかの漢字表記があり、梵語（サンスクリット語）で「vajra金剛石（ダイアモンド）」を意味するが、意味の転化は不明であるとされる。