Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
imperturbable is an adjective meaning "not easily perturbed or excited or upset; marked by extreme calm and composure". It carries one recorded sense.
not easily perturbed or excited or upset; marked by extreme calm and composure
“hitherto imperturbable, he now showed signs of alarm”
“an imperturbable self-possession”
“unflappable in a crisis”
Definitions, synonyms and semantic relations for imperturbable come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.