The crossword solution for the term 'Trainer or Professor, for short' is INSTR, which is an abbreviation for instructor. An instructor is a person who teaches a skill or provides instruction in a particular subject. They are often employed in educational institutions such as universities, colleges, and schools, but can also be found in other settings such as corporate training programs. Instructors are typically responsible for providing guidance to students, helping them to understand concepts, and providing feedback on their progress.