Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
nervelessly is an adverb meaning "in a composed and unconcerned manner". It carries one recorded sense.
in a composed and unconcerned manner
“without more ado Barker borrowed a knife from his brigade Major and honed it on a carborundum stone as coolly as a butcher”
Definitions, synonyms and semantic relations for nervelessly come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.