unacceptable

adjective

un·​ac·​cept·​able ˌən-ik-ˈsep-tə-bəl 

-ak-

: not acceptable : not pleasing or welcome

unacceptability

ˌən-ik-ˌsep-tə-ˈbi-lə-tē 

noun

unacceptably

ˌən-ik-ˈsep-tə-blē 

adverb

Synonyms of unacceptable

• wrong
• poor
• lame
• bad
• horrible
• terrible
• deficient
• awful
• unsatisfactory
• flawed
• disastrous
• pathetic

Examples of unacceptable in a Sentence

a word that is unacceptable in formal English

Some of her ideas were unacceptable to other people.

Recent Examples on the Web

Still, only 28% of readers said that AI use is unacceptable in all of the circumstances presented by the survey. — Cameron Pugh, Christian Science Monitor, 12 Aug. 2026

Intervene Intervene means several signals—or one sufficiently consequential event—indicate probable deterioration or unacceptable outcomes. — Gerald J. Leonard, Forbes.com, 10 Aug. 2026

The prospect of such leverage is unacceptable in Washington, Abu Dhabi and Riyadh. — Todd Symons, CNN Money, 6 Aug. 2026

Given the national security stakes, the prospect of foreign governments being able to suspend access to critical models at a whim started to feel like an unacceptable risk. — Beatrice Nolan, Fortune, 5 Aug. 2026

Word History

First Known Use

15th century, in the meaning defined above

Rhymes for unacceptable

• acceptable
• perceptible
• susceptible
• imperceptible

Kids Definition

unacceptable

adjective

un·​ac·​cept·​able ˌən-ik-ˈsep-tə-bəl 

-ak-

: not acceptable : not pleasing or welcome

unacceptably

-blē 

adverb