Nonsensical means making no sense at all, being completely illogical or absurd. When something is nonsensical, it's so confused or ridiculous that you can't find any reasonable meaning in it.

If your friend claims that penguins live in the desert and eat ice cream for breakfast, that's a nonsensical statement. It contradicts basic facts about the world. If someone gives you directions like “turn left at the invisible tree, then walk backward through the purple doorway,” those instructions are nonsensical because they're impossible to follow.

The word often describes language or ideas that sound like they should mean something but actually don't. A sentence like “The Tuesday swims loudly in my shoe” uses real words arranged in grammatical order, yet it's completely nonsensical. Similarly, if someone strings together big, impressive-sounding words without any clear point, you might say their argument is nonsensical.

Teachers sometimes describe an answer as nonsensical when a student has written something that doesn't address the question at all, or when an explanation contradicts itself so badly that it can't possibly be right. The related noun is nonsense, which means foolish or meaningless words and ideas.