Present participle of commune: sharing intimate thoughts and feelings, or experiencing spiritual connection with something.
From 'commune' (verb) from Old French 'comuner' (to share together). The spiritual sense developed in Romantic poetry.
Walden Pond where Thoreau lived has become a pilgrimage site because he wrote so beautifully about 'communing with nature'—the word itself seems to require a natural or spiritual context, which is linguistically fascinating.
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