Nonsense (noun)

1. Words or language that are meaningless or that make no sense.
2. Behavior or actions that are irrational or senseless.

Origin:

From middle english non-sense "lack of sense", from old english non "not" + sense "sense".

Examples:

1. He was talking nonsense and no one could understand him.
2. It"s all nonsense, there"s no scientific evidence to back it up.
3. The idea that aliens built the pyramids is complete nonsense.
4. The argument is nothing but a bunch of nonsense.
5. Stop talking nonsense and focus on the task at hand.