Syllable division and stress derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
soughingly is an adverb meaning "with a soft sound". It carries one recorded sense.
with a soft sound
“the branches of the trees moved soughingly in the breeze”
Definitions, synonyms and semantic relations for soughingly come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.