Unintelligible – Impossible to understand
"Understanding intelligent people is impossible", (unintelligible) said the young student. "They are impossible to understand".
Examples of unintelligible in a sentence
Animal sounds are unintelligible to humans but we can use body language to figure out what they want.
The doctors notes were unintelligible, as usual.
I like all the music by this singer, but the lyrics are completely unintelligible.