I have never seen a definition. In our parish,at night, especially on Holy Days other than Sunday, Our pastor holds a Bilingual Mass. (English and Spanish) the lectors read one reading in English and one in Spanish. The psalm is usually in English. The deacon reads the Gospel in English and Spanish. The Homily is given in both languages…makes for a little longer Mass. The prayer of the faithful is in English. Various other parts of the Mass alternate between English and Spanish. The music also alternates sometimes.
We are one body in this whole world.