The sport, practice, or philosophy of boxing; or the Chinese Boxer Rebellion and its ideologies (historical).
From 'boxer' (one who practices boxing) plus '-ism' (a system or belief). The historical sense refers to the 1900 Boxer Rebellion in China.
The Boxer Rebellion was named 'boxing' by Westerners because the rebels practiced martial arts—but their actual name meant 'Righteous and Harmonious Fists,' showing how names get lost in translation and history!
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