Many Third World countries are facing economic challenges.

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

The minor third is an interval of three half steps.

He wrote that novel in third person.

Third time's the charm.

He suffered a third-degree burn on his hand.

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.