From Norman French, "face, merry faces, festivity"; from Late Latin, "head".

The sense of smiling, merry expression, good cheer, cheerful, is well attested in literature. "Cheers" is a versatile modern expression. I have heard it as "thanks", "drink well" (of course), and yes even "see you later".

permo-w 5 days ago | parent [-]

>and yes even "see you later".

this being my point. how do you know that what you were hearing wasn't someone saying thanks as they were leaving?

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xanderlewis 5 days ago | parent [-]

I think you’re right. You do (or, at least, when I imagine it in my head, I do) hear it frequently used when saying goodbye, but I don’t think it would be used to say goodbye.

If someone said ‘cheers’ to me when parting, I’d interpret it the same way as if they’d said ‘thanks’ — which could be slightly strange, depending on the situation.

	▲	heresie-dabord 4 days ago \| parent [-]
		https://en.wiktionary.org/wiki/cheerio Maybe it is a conflation of cheers (smiles, thanks) and cheerio (old-fashioned familiar good-bye).