WordWeb Online

1. Not acceptable; not welcome
   "a word unacceptable in polite society"; "an unacceptable violation of personal freedom"
    
2. Not adequate to give satisfaction
   "the coach told his players that defeat was unacceptable"
    
3. (of a person or group of people) very annoying, unreasonable or difficult to deal with
   "unacceptable behaviour";
   - impossible
    
4. (linguistics) not conforming to standard usage
   "the following use of 'access' was judged unacceptable by a panel of linguists; 'You can access your cash at any of 300 automatic tellers'";
   - unaccepted

See also: exceptionable, intolerable, nonstandard, objectionable, unbearable, unendurable, unsatisfactory, unwelcome, unwished, unwished-for

Antonym: acceptable

Encyclopedia: Unacceptable