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1726 (implied in gambling), from a dialectal survival of Middle English gammlen, variant of gamenen "to play, jest, be merry," from Old English gamenian "to play, joke, pun," from gamen (see game). Or possibly gamble is from a derivative of gamel "to play games" (1590s), itself likely a frequentative from game. Originally regarded as a slang word. The intrusive -b- may be from confusion with gambol. Related: Gambled; gambling.
"risky venture," 1823, from gamble (v.).