(idiomatic) A private personal detective, employed to gather information about someone.

Of a corporation or other business, owned by a small number of people, and not having shares of ownership sold via a stock exchange or other public market.

The unpublished key in asymmetric cryptography.

plural of private school

A fee-charging private or independent school.

(colloquial) A private investigator; a private detective.

Any agent hired by a private party for the purpose of investigation or evidence gathering.

plural of private candidate

(Britain) One who enters an examination without being enrolled as a student at the educational establishment where it is given.

(US, military slang) A private soldier keen ("bucking") for promotion; an ambitious private.