Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
untactful is an adjective meaning "lacking or showing a lack of what is fitting and considerate in dealing with others". It carries one recorded sense.
lacking or showing a lack of what is fitting and considerate in dealing with others
“in the circumstances it was tactless to ask her age”
Definitions, synonyms and semantic relations for untactful come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.