Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
undiagnosable is an adjective meaning "not possible to diagnose". It carries one recorded sense.
not possible to diagnose
Definitions, synonyms and semantic relations for undiagnosable come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.