In a direction downward and to the side; in a lower location nearby (primarily Scottish/Northern English dialect).
From 'down' (downward) plus 'by' (near, beside); a dialectal compound preposition common in Scots and Northern English for describing relative location.
Scottish and Northern English speakers created these wonderful precise location words—'downby' is different from 'down there' because it's specifically downward AND beside! Studying dialect words like this shows how different communities developed unique ways to describe their landscapes.
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