Cheers

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Middle English: from Old French chiere ‘face’, from late Latin cara, from Greek kara ‘head’. The original sense was ‘face’, hence ‘expression, mood’, later specifically ‘a good mood’.

wiktionary

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etymonline

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cheers

salute or toast when taking a drink, British, 1919, from plural of cheer (also see cheerio). Earlier it is recorded as a shout of support or encouragement (1720).