dunno/ˈdʌnəʊ/EtymologyWritten form of an informal pronunciation of don't know that is a reduction of do not know or does not know.dunno means an utterance of the word dunno. Lexicurio rates it Rare gem — a strength score of 81 out of 100.dunno is pronounced /ˈdʌnəʊ/.nounAn utterance of the word dunno.