In a manner resembling or relating to raccoons, or in the style of raccoon hunting.
From coony (adjective) with the addition of the adverb-forming suffix -ly, creating an adverb that describes how something is done or how something appears.
Adding -ly to create adverbs is one of English's most productive patterns, but 'coonily' is so specialized that it rarely appears outside of hunting communities and historical frontier texts.
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