wiktionary
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A 1960s compound of kick + boxing. Possibly coined as a Japanese anglicism ( 和製英語), キックボクシング(kikkubokushingu) by Osamu Noguchi, to be reborrowed into English.
etymonline
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kickboxing (n.)
also kick-boxing, 1968, from kick (n.) + boxing (n.). Related: Kickbox (v.); kickboxer (1978).
