Hush-hush and In camera

Hush-hush adjective - Not known or meant to be known by the general populace.

In camera and hush-hush are semantically related In some cases you can use "In camera" instead the phrase "Hush-hush" as an adverb or an adjective.

In camera adverb - In a manner intended to prevent knowledge or awareness by others.

Hush-hush and in camera are semantically related in clandestine topic. You can use "Hush-hush" instead the phrase "In camera" as an adverb or an adjective, if it concerns topics such as secretly, in hidden manner.