How do you know which way to spell course as in of course and what are the two ways to spell course?

The homophones (sound-alike Words) are course and coarse.

The only uses of the adjective "coarse" are to mean rough, vulgar, low quality, or not finely ground.

E.g. coarse sandpaper, coarse language, coarse pepper

The Word "course" (as in of course) is usually a noun with related meanings:

- a path, a direction, or route, as in Golf course, watercourse, or ship's course

- the flow of time (course of events)

- a curriculum, progression, step, or series (college course, course of treatment, a dinner course)

It can also more rarely be a verb meaning to flow (the water courses through the aqueduct, tears coursing down a face)

The idiom "of course" means certainly, as if in a natural progression or path.

The phrase "in due course" means eventually, but not immediately; at the proper time.