General Antonyms:
* Orderly
* Organized
* Structured
* Systematic
* Calm
* Peaceful
* Harmonious
Specific Antonyms:
* Controlled (if the chaos is due to a lack of control)
* Predictable (if the chaos is due to unpredictability)
* Stable (if the chaos is due to instability)
* Serene (if the chaos is due to a lack of peace)
The best antonym to use depends on the specific situation and the type of chaos being described.