It can be, depending on how you use it in a sentence. It can also be a verb.
Course is a noun. It refers to a direction or class.
its a noun (of course)
The plural of course is courses.
No. It is a noun (ship's course, golf course, river course). The meaning is a path, route, or progression. Course is a noun-adjunct in the term 'three course meal' (each stage of the meal is a course or path).
yes, of course!
Routine is a noun - a regular course of procedure
A collective noun for treatment is a course of treatment.
Yeah, of course!
No, it is not a preposition. The word course is a noun, or a verb (to flow).
Course is a noun. It refers to a direction or class.
The word "course" is a common noun. It refers to a path or direction considered to be taken.
Undergraduate can be an adjective or a noun. Noun -> The undergraduate failed the course. Adjective -> The freshman failed the undergraduate course.