An archaic or historical term, possibly referring to a carefree person or reveler (etymology uncertain; may be obsolete or regional dialect).
Possibly from heyday (a period of prosperity or merriment) + guy, though this appears to be an extremely rare or potentially fabricated term with unclear historical documentation.
This word is so obscure that even comprehensive historical dictionaries barely mention it—it's a reminder that thousands of words have vanished from English, leaving only faint traces for language detectives to puzzle over.
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