Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
unassertive is an adjective meaning "inclined to timidity or lack of self-confidence". It carries one recorded sense.
inclined to timidity or lack of self-confidence
“a shy unassertive person”
Definitions, synonyms and semantic relations for unassertive come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.