What word means the opposite of captive?

There isn't one single perfect opposite for "captive" because it depends on the context. Here are some options depending on what you're looking for:

If you mean "not imprisoned":

* Free

* Unbound

* Released

* Independent

If you mean "not forced to stay":

* Voluntary

* Willing

* Eager

If you mean "not under control":

* Autonomous

* Independent

* Self-governing

The best word for you will depend on the specific situation you're describing.