Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
unhardened is an adjective meaning "not brought to a proper consistency or hardness". It carries one recorded sense.
not brought to a proper consistency or hardness
“untempered mortar”
“untempered steel”
Definitions, synonyms and semantic relations for unhardened come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.