Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
unsufferable is an adjective meaning "too extreme to bear". It carries one recorded sense.
too extreme to bear
“the insufferable heat of August in a New York apartment with no air conditioning”
Definitions, synonyms and semantic relations for unsufferable come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.