This paper is a perfect square.

This table is tetragon in shape.

Japan's feudal system was the foundation of the socio-economic structure in the Middle Ages.

He wrote his name on the paper.

This plan was perfectly successful.

This project has been completed in its entirety.

Feudalism dominated medieval European society.

You can see a beautiful view from this rectangular window.

He decided to have surgery for phimosis.

He is scheduled to have surgery for phimosis.