In a manner that involves separating compound things; in a way that breaks down mixed elements.
From decompound + -ly (manner adverb suffix). This is a rarely used adverb form that modifies verbs or adjectives related to decompounding.
This is one of those ultra-specific adverbs that probably hasn't been used in centuries—it's a linguistic relic showing how English-speakers once had precise words for now-forgotten concepts.
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