1. Course (as in a path or route):
* Coarse: Rough or unrefined.
2. Course (as in a series of lessons):
* Coarse: Rough or unrefined.
* Cors: (Archaic) A kind of wild pigeon.
3. Course (as in a part of a meal):
* Coarse: Rough or unrefined.
* Cors: (Archaic) A kind of wild pigeon.
4. Course (as in the direction of a ship):
* Cors: (Archaic) A kind of wild pigeon.
So the best homonym for "course" will depend on the specific context of your sentence.