Of or pertaining to forests; characteristic of or resembling a forest; having the nature of woodland.
From 'forest' + '-ian' (a suffix forming adjectives and nouns), likely a rare or literary formation attempting a more elegant way to describe forest-like qualities.
This is essentially a very high-minded and poetic way to say 'foresty'—the kind of word a Romantic-era poet might have invented to make a forest sound mysterious and grand.
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