Le roi malgré lui ("King in Spite of Himself" or "The reluctant king") is an opéra-comique in three acts by Emmanuel Chabrier of 1887 with an original libretto by Emile de Najac and Paul Burani. The opera is revived occasionally, but has not yet found a place in repertory.
The opera is in French.
The title is in French and written by someone French, so this is the most likely language.