Direct opposites:
* Nonsensical: This is the most direct opposite, meaning something that makes no sense at all.
* Absurd: This implies a degree of illogicality or ridiculousness.
* Incoherent: This describes something that lacks clarity or logic.
Other opposites:
* Unintelligible: This refers to something that cannot be understood.
* Meaningless: This implies a lack of significance or purpose.
* Irrational: This suggests a lack of reason or logic.
* Illogical: This implies a lack of sound reasoning.
The best word to use will depend on the specific meaning you want to convey.