Word parts change

un- + acceptable + -ly
unacceptable + acceptablely

Pronunciation change

Adverb change

Positive
unacceptably

Comparative
more unacceptably

Superlative
most unacceptably

  1. Not within the limits of what is generally considered to be acceptable; alternatively, within the limits of what is generally considered to be unacceptable
    The levels of lead in marine hull paints are still unacceptably high.
    Your comments are unacceptably provocative.