If something is semiprivate, it is only a little private, not completely private.
Semiprivate things are kind of private, but not totally. It's like a little secret.
Examples:
The hospital room was semiprivate, so there were only a few other people in it.
The semiprivate beach was not too crowded, but it wasn't completely empty either.
The semiprivate club had a special area just for some people.
The semiprivate party was almost like a secret club!
The semiprivate garden was only for some people, not everyone.
The semiprivate room was like a little secret hideout.