unintelligible
adj.adj. impossible to understand because the speech or writing is not clear. You use this when someone is mumbling or the handwriting is very messy.
adj. impossible to understand or comprehend, typically due to poor articulation, low audio quality, or illegible script. Often used predicatively after linking verbs like 'be', 'become', or 'sound'.
His handwriting is so messy that it is almost unintelligible.
The recording was so old and scratchy that most of the interview remained unintelligible to the researchers.
While the technical jargon was familiar to the engineers, the dense mathematical proofs in the appendix were largely unintelligible to the lay audience attending the lecture.
Often follows a linking verb or modifies nouns related to communication like 'speech', 'writing', or 'sounds'.
The book was unintelligible to read.The book was unintelligible.Unintelligible describes the quality of the communication itself; adding 'to read' is redundant and grammatically awkward.