"A huis clos" is a French expression that means "behind closed doors." It implies that something is happening in secret or without public access. There are several synonyms for this phrase, including "behind the scenes," "in camera," "in private," "confidentially," and "off the record." Each of these phrases implies that whatever is happening is not meant for public consumption or scrutiny. They suggest that the information being discussed or the actions being taken are intended for a select group of people and are not to be shared with outsiders. Thus, these synonyms provide a sense of exclusivity and confidentiality to whatever is happening "a huis clos".