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