In a bulldoggish manner; with stubborn, aggressive persistence and refusal to yield or release.
From 'bulldoggish' (adjective) + '-ly' (adverb-forming suffix). This creates an adverb describing the manner in which something is done with bulldog-like qualities.
This adverb lets us describe actions taken with that special kind of stubborn persistence—'he bulldoggishly pursued the lead' captures not just persistence but an almost aggressive refusal to accept failure.
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