Title and form of address for learned or skilled individual
A fellow is a title and form of address for distinguished, learned, or skilled individuals in academia, medicine, research, and industry. The exact meaning of the term differs in each field. In learned or professional societies, the term refers to a privileged member who is specially elected in recognition of their work and achievements. Within institutions of higher education, a fellow is a member of a highly ranked group of teachers at a particular college or university or a member of the governing body in some universities.
https://en.wikipedia.org/wiki/Fellow