What does "nonsense" mean?

Interpretation: unfounded and unreasonable nonsense.

Sentence: Don't listen to him. He just made something out of thin air.

"What is the third generation? Nonsense! " Gander answered angrily.

It is also a pain to have to sit in the classroom and listen to the bishop's nonsense on Sunday morning.

Look at him talking nonsense in front of the teacher. What he said was a casual remark, which made the teacher think how bad I was!

The fortune teller talked nonsense and cheated money.