From Middle English unacceptabylle, equivalent to un- + acceptable.

• (British) IPA: /ˌʌn.æk.ˈsɛp.tə.bl̩/, /ˌʌn.ək.ˈsɛp.tə.bl̩/, [ˌɐn.æk.ˈsɛp.tə.bɫ̩], [ˌɐn.ək.ˈsɛp.tə.bɫ̩]
• (America) IPA: /ˌʌn.æk.ˈsɛp.tə.bl̩/, /ˌʌn.ək.ˈsɛp.tə.bl̩/, [ˌɐn.æk.ˈsɛp.tə.bɫ̩], [ˌɐn.ɪ̞k.ˈsɛp.tə.bɫ̩]

unacceptable

1. unsatisfactory; not acceptable
2. (linguistics) not conforming to accepted usage

• inacceptable (less common)

• acceptable

• French: inacceptable
• German: inakzeptabel
• Italian: inaccettabile, inammissibile, intollerabile, ingiustificabile
• Portuguese: inaceitável
• Russian: неприе́млемый
• Spanish: inaceptable, no ser de recibo

unacceptable (plural unacceptables)

1. Something that is not acceptable.
   • 1989, Walter A. Henry, Michael Menasco, Hirokazu Takada, New-product Development and Testing, page 106:

     Second, the data collected using CASEMAP afford us the opportunity to conduct market segmentation analyses based on the similarity in the pattern of unacceptables and/or the benefits that consumers seek in the category.