Archaic or obsolete form meaning nowadays or in these present days; in modern times.
From 'a-' plus the plural 'days'; constructed as 'at days' meaning 'in the present period,' used by Middle English speakers to mean 'currently.'
Medieval writers said 'adays' to mean 'nowadays,' and we still understand it because the logic is transparent—but only barely, since English has mostly shed these 'a-' adverbial prefixes.
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