In a barren manner; in a way that is empty, bleak, or unproductive.
From barren plus -ly, the common English adverb suffix that turns adjectives into adverbs. This formation is entirely regular and productive in English.
The word barrenly captures something poetry loves—the desolate mood of empty landscapes—and appears in Romantic literature describing windswept moors and abandoned terrain as if the word itself sounds lonely.
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