In a heavy, substantial, or forceful manner; with considerable weight or effort.
Adverb formed from 'hefty' plus the -ly suffix, which is English's primary mechanism for converting adjectives into adverbs describing how an action is performed.
Adverbs are like the invisible choreography of language—'heftily' tells us not just what happened, but the quality of effort and weight behind the action. It adds texture to the narrative.
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