A proper noun is a noun that refers to a specific person, place, or thing.

This eigenfunction is one of the fundamental concepts of quantum mechanics.

This dish uses cottonseed oil.

He received an exemption from taxes.

He was exempted from the exam.

He was exempted from the exam.

I use cottonseed oil in salad dressing.

The flavor improves when you use cottonseed oil in cooking.

My driver's license has been renewed.

His new car is yellow-green.