He traveled in the third-class cabin on the ship.

The food at that restaurant is third-rate.

The minor third is an interval of three half steps.

I hired a third party to handle the negotiations.

He suffered a third-degree burn on his hand.

Third time's the charm.

He was promoted to petty officer third class.

The detective gave the suspect the third degree during the interrogation.

Thirdly, if you don't put in the effort and challenge difficult things, there is nothing in the world at which you will succeed.