Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
vanishingly is an adverb meaning "so as to disappear or approach zero". It carries one recorded sense.
so as to disappear or approach zero
“errors are vanishingly rare”
Definitions, synonyms and semantic relations for vanishingly come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.