In a manner that acknowledges or concedes a point; expressing concession through language or tone.
From concessive plus the adverbial suffix -ly. This adverb describes how something is done or expressed with an acknowledgment of an opposing viewpoint.
When someone says 'concessively, I understand your point, but...' they're linguistically preparing you for disagreement—the adverb signals they're about to agree while actually disagreeing. It's a verbal fence-straddler.
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