a feasible arrangement or practical compromise; esp : one that bypasses difficulties

Pronunciation:
MOE-dus vih-VEN-dee

In a sentence:
Lisa and her students agreed on a modus vivendi which would allow both parties to enjoy some stress relief during exam time; they would leave her alone with her bourbon during office hours, and she would conveniently forget every letter of the alphabet but the first by semester’s end. 

In a different sentence:
The established modus vivendi would allow both countries to use deadly force on the other at any time. Everyone was really happy.