Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
mandatorily is an adverb meaning "in a manner that cannot be evaded". It carries one recorded sense.
in a manner that cannot be evaded
“the ministry considers that contributions to such a fund should be met from voluntary donations rather than from rates compulsorily levied.”
Definitions, synonyms and semantic relations for mandatorily come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.