Persona non grata
Persona non grata or an ingrate person is a Latin expression literally meaning an unwelcome person.
Is a common legal term used in diplomacy that indicates a interdiction against a person entering the country. It is the most serious form of censure which one country can apply to foreign diplomats, who are otherwise protected by diplomatic immunity from arrest and other normal kinds of prosecution.
In everyday speech the term refers to a person who is excluded from a certain circle.
The antonym of persona non grata is persona grata or persona gratissima.