In a manner of existing; in a way that relates to being or existence (archaic or rare form).
From existent (existing) with the adverbial suffix -ly. This is a less common variant or historical form compared to the more standard existentially.
This is a rare word that shows English speakers centuries ago tried to say 'in an existing way'—it's been mostly replaced by existentially, but it's a great window into how English evolved!
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