means A senior academic teacher at a university, typically the highest-ranking instructor in their field and responsible for teaching and research.

from From Latin professor, 'one who declares publicly,' built from profiteri, 'to profess or declare openly' (pro-, 'forth' + fateri, 'to acknowledge'). The same root gives us 'profess' and 'profession' — originally the idea was someone who publicly avowed their expertise, a cousin of the word for declaring religious vows. It entered English by the late Middle Ages as a title for a recognized master of a subject.