Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
obstreperously is an adverb meaning "in manner that attracts attention". It carries one recorded sense.
in manner that attracts attention
“obstreperously, he demanded to get service”
Definitions, synonyms and semantic relations for obstreperously come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.