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.

We need to think of a strategy to maximize profits.

We need to come up with a new strategy to maximize profits.

We will make the maximum effort for the success of this project.

The Empire of Japan, written as 大日本帝國 in Kyūjitai, was a nation that existed from 1868 to 1945.

The Imperial Japanese Army was a Japanese military force that existed from the Meiji era to the Showa era.

The Imperial Japanese Navy was once the navy of Japan.

I achieved a big success.

He graduated from the University of Tokyo.