Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
undestroyable is an adjective meaning "very long lasting". It carries 2 recorded senses.
very long lasting
“less durable rocks were gradually worn away to form valleys”
“the perdurable granite of the ancient Appalachian spine of the continent”
not capable of being destroyed
Definitions, synonyms and semantic relations for undestroyable come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.