(of words or language) having little or no meaning; making little or no sense: A baby's babbling is appealingly nonsensical. (of behavior, conduct, actions, etc.) foolish, senseless, fatuous, or absurd: His nonsensical behavior was unusual for such a serious person.

What is an example of nonsensical?

The definition of nonsensical is something silly or that doesn't make sense. An example of nonsensical is a story about a flying pink elephant jumping through a window.

What is the difference between nonsense and nonsensical?

If something is nonsense, then it's just vaguely somewhere in the realm of what is silly/stupid/pointless...; but when you describe something as nonsensical you are saying that it lacks sense.