In a manner that wears down or gradually diminishes; in an attritive way (rare or potentially misspelled).
Possibly from attritive + -ly suffix, though this appears to be an extremely rare formation or may be a variant spelling/typo of 'attributively' (a more common adverb in grammar).
This word is so obscure (or possibly misspelled) that even historical dictionaries struggle with it—it might be a 'ghost word' that slipped into texts as a typo and then got copied into references!
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