Former, previously, or some time ago; an archaic or poetic term for 'erstwhile.'
From Old English 'ær' meaning 'before' combined with 'while' meaning 'a period of time,' literally 'before the while' or 'before this time.' It evolved to mean 'formerly' or 'previously.'
Medieval writers loved 'erewhile' because it sounded more archaic and formal than simple 'before,' giving their narratives a deeper sense of time passing—which is why Shakespeare and earlier poets peppered it throughout their works.
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