Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
unrealised is an adjective meaning "of persons; marked by failure to realize full potentialities". It carries one recorded sense.
of persons; marked by failure to realize full potentialities
“unfulfilled and uneasy men”
“unrealized dreams and ambitions”
Definitions, synonyms and semantic relations for unrealised come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.