Slight tangent - but the term 'professor' in Commonwealth academia is a grade - a rank, if you will. The progression is something like this:
Junior lecturer
Lecturer
Senior lecturer
Assistant Professor
Professor.
On retirement they can be appointed Professor Emeritus
Some universities have a variation on this - using terms such as 'Reader' etc. However, in the US system (and I don't know about the other America), all university lecturers refer to themselves as 'professors'. The ex Black Watch and ex FCO diplomat MP Rory Stewart referred to himself as having been a Harvard Professor. In reality, he had a semester or two as a visiting junior lecturer.
Just thought I'd mention this.