English dictionaryunacceptable noun Copy definition Share Print / Save as PDFPronunciation /ˌʌn.æk.ˈsɛp.tə.bl̩/Parts of speech noun adjectiveDefinitionsnounSomething that is not acceptable.adjectiveUnsatisfactory; not acceptableNot conforming to accepted usageSynonyms inacceptableAntonyms acceptable