unintelligible

Unintelligible is an adjective used to describe speech, writing, or other communications that cannot be understood or interpreted. In everyday use, it is applied when the intended message is not recoverable by a listener or reader given the available signal and context. Intelligibility depends on both the quality of the signal and the listener’s abilities, knowledge, and expectations, so what is unintelligible to one person may be comprehensible to another.

In spoken language, factors that can render utterances unintelligible include rapid delivery, heavy or unfamiliar accents, misarticulation, mumbling, slurring, cognitive impairment, intoxication, fatigue, and environmental noise or acoustic interference. In such cases, listeners may miss words, misinterpret phrases, or fail to parse the intended syntax. In written language, illegibility or garbled text can result from poor handwriting, typographical errors, encoding issues, damaged documents, or transcription mistakes.

Unintelligibility is often assessed through perceptual judgments or experimental measures of how well content can be understood under certain conditions. In clinical settings, speech-language pathologists evaluate intelligibility to diagnose and treat communication disorders. In research and technology, automatic methods may estimate intelligibility for speech recognition or comprehension tasks. It is important to note that unintelligibility does not always equate to lack of meaning; unfamiliar languages, dialects, or code systems may be perfectly meaningful within their own communities.

Etymology: from un- + intelligible, derived from Latin intelligibilis. Related terms include incomprehensible, indecipherable, garbled, and illegible. See also intelligibility, speech disorders, and cryptic or dialectal variation.