To neighbor or be adjacent to something; a variant or archaic form meaning to live nearby or be in proximity to.
From 'co-' (together) plus 'neighboring,' a constructed word suggesting the act of being neighbors together, though this is an archaic or extremely rare usage.
This word is so obscure that even comprehensive dictionaries barely mention it—it's a perfect example of how English creates new words by combining prefixes and common words, most of which never stick around.
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