In a manner that involves or expresses confession; with confession or admission.
From confessing (present participle of confess) + -ly (adverbial suffix). The -ing participle form combined with -ly creates an adverb describing how something is done.
Confessingly is a rare adverb that shows English speakers' creativity—while it appears in historical texts, it was never standardized, making it a window into how English wordbuilding works even when a word doesn't become common.
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