A person or thing has either not made a debut, is making a debut, or has already made a debut.... there is no opposite.
Perhaps you are thinking "unreleased" as in an song or video that has not been made public or has not debuted.
The opposite of opposites is similarities or likenesses.
Neelam Kothari
If you have to be opposite on opposite day, that makes it a day, and then there was no opposite day. But that can't be true since you HAVE to be opposite, which means that you have to be normal even...
Opposite of Up is down. So, opposite of the opposite of Up is Up itself.