In an excrescent manner; with excessive or abnormal growth; superfluously.
Adverbial form of excrescent, using the -ly suffix to convert the adjective into an adverb describing how something grows or appears.
You might describe a plant growing 'excrescently' when it sprouts weird lumpy growths instead of leaves, or describe a story's plot developing 'excrescently' when subplots keep awkwardly branching off.
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