In a manner that is doubtfully authentic, questionably genuine, or in the style of apocryphal texts.
From apocryphal with the adverbial suffix -ly, forming an adverb that describes actions or statements done in a dubious or unverified manner.
When historians say something is told 'apocryphally,' they're basically saying 'probably didn't happen exactly like that, but it's a good story anyway!'
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