General antonyms:
* Unlimited
* Boundless
* Unrestricted
* Extensive
* Comprehensive
* Unconfined
More specific antonyms:
* Abundant (if referring to quantity)
* Infinite (if referring to quantity)
* Vast (if referring to size)
* Open (if referring to access)
* Free (if referring to restrictions)
Example:
* Limited time: Unlimited time, Open-ended time
* Limited resources: Abundant resources, Vast resources
To choose the most appropriate antonym, consider the specific meaning of "limited" in the sentence you are using.