General opposites:
* Unintelligible: This is the most straightforward opposite, meaning something that is impossible to understand.
* Incomprehensible: Similar to unintelligible, but emphasizing a complete lack of understanding.
* Obscure: Meaning something that is unclear or difficult to understand.
* Inscrutable: Describing something that is impossible to understand or interpret.
* Abstruse: Something that is very difficult to understand, usually because it is complex or esoteric.
More specific opposites:
* Vague: Lacking clarity or precision.
* Ambiguous: Open to multiple interpretations, making understanding difficult.
* Confusing: Causing confusion or misunderstanding.
* Unclear: Not easily understood or interpreted.
* Meaningless: Having no significance or purpose.
The best opposite will depend on the specific situation and the intended meaning.