In an aggressive, hostile, or warlike manner; with combative or quarrelsome behavior.
From 'belligerent' (Latin 'bellum' + 'gerere') plus the adverbial suffix '-ly', creating an adverb form that describes how an action is performed aggressively.
This adverb perfectly captures how someone can act—not just be—aggressive; someone might belligerently shake their fist or belligerently refuse to cooperate, turning an internal state into observable behavior.
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