'banzai' originates from Japanese, specifically the word '万歳' (ばんざい), where the characters mean 'ten thousand years' and the phrase was used to wish long life or express celebration.

'万歳' comes from Chinese 'wànsuì' (萬歲), meaning 'ten thousand years' (a wish for longevity or long reign); the phrase was adopted into Japanese and later borrowed into English in the 19th and 20th centuries, becoming 'banzai' in modern English.

Initially, it literally meant '10,000 years' (a wish for long life or long reign); over time in Japanese it became a general celebratory cry meaning 'long live' or 'hooray', and in English it kept the sense of an exclamation of cheer and also acquired a specialized military sense ('banzai charge').