When do you use Emeriti?

This is the Latin plural of Emeritus. In universities, a professor who has been with that school for many years and is now retired is often awarded the honorary title of Professor Emeritus. (Some schools use Emerita if it's a female, where others use Emeritus for both males and females.) But if we are referring to more than one of these retired professors, we would use the plural for both: Dr. Smith and Dr. Jones are both Professors Emeriti at Harvard University.