unacceptable

British

/ ˌʌnəkˈsɛptəbəl /

adjective

not satisfactory; inadequate

the standard was wholly unacceptable
intolerable

hitting children is unacceptable

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Explanation

Something unacceptable is not okay — it's objectionable or displeasing. Hey, are you yelling in the library? That's unacceptable! If a student's behavior is unacceptable, she may get detention or be sent to the principal's office. And if a restaurant patron's meal is unacceptable, he has every right to ask his server for something else. The adjective unacceptable adds the "not" prefix un- to acceptable, "suitable, adequate, or pleasing." We can trace the roots back to the Latin acceptare, "take or receive willingly."

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

He said his his team's performance in the defeat by Brighton was both "indefensible" and "unacceptable".

From BBC • Apr. 22, 2026

Lowri Mair Williams is facing a fitness to practice hearing over unacceptable conduct while girls' rugby lead at Llandovery College, Carmarthenshire.

From BBC • Apr. 21, 2026

Education Secretary Bridget Phillipson said "freedom of speech is the foundation of every university's success" but there had been too many cases contributing to "an unacceptable culture of fear and stifling the pursuit of knowledge".

From BBC • Apr. 19, 2026

“He was incredibly brave to come forward and to be a plaintiff ... To be targeted because he is pursuing his rights is unacceptable, but not surprising given what we’ve been seeing.”

From Los Angeles Times • Apr. 17, 2026

The thought of leaving the children alone while the search party was still at large had been simply unacceptable to her.

From "The Incorrigible Children of Ashton Place: Book I: The Mysterious Howling" by Maryrose Wood

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023