General opposites:
* Free
* Unbound
* Open
* Spacious
* Unrestrained
* Unrestricted
More specific opposites:
* Spacious (if referring to physical space)
* Liberated (if referring to freedom from restrictions)
* Expansive (if referring to a sense of limitless possibilities)
* Unlimited (if referring to a lack of boundaries)
Example:
* Confined: The prisoner felt confined in his cell.
* Opposite: The bird felt free to fly after being released from its cage.
Ultimately, the best opposite for "confined" depends on the specific situation and what you want to emphasize.