lingua franca

noun1

1. •
   A common language used by people of diverse backgrounds to communicate with one another, often a basic form of speech with simplified grammar, particularly, one that is not the first language of any of its speakers.

   • Taking these cues, I rewrote and rewrote the proposal couching my problem in the bland, euphemistic language that I was rapidly learning is the lingua franca of the corporate world. — 1988