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