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

The group Save Our Beaches San Clemente, however, says adding more rocks on the coast to protect the railroad is unacceptable. — Los Angeles Times, 28 Sep. 2026

Russia's demands for Ukraine to surrender its territory, among other things, are unacceptable for Kyiv. — Hanna Arhirova, Arkansas Online, 25 Sep. 2026

For the United States and its partners, meanwhile, the economic and military costs of the war are becoming unacceptable. — Richard Haass, Foreign Affairs, 23 Sep. 2026

In one place, a behavior is permissible or even encouraged, while in another, that same behavior is unacceptable and has negative consequences. — Dr. Monika Sumra, Forbes.com, 22 Sep. 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