Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
unattackable is an adjective meaning "immune to attack; incapable of being tampered with". It carries one recorded sense.
immune to attack; incapable of being tampered with
“an impregnable fortress”
“fortifications that made the frontier inviolable”
“a secure telephone connection”
Definitions, synonyms and semantic relations for unattackable come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.