Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
diffident is an adjective meaning "showing modest reserve". It carries 2 recorded senses.
showing modest reserve
“she was diffident when offering a comment on the professor's lecture”
Definitions, synonyms and semantic relations for diffident come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.