Hairy describes something covered with hair or having a lot of hair. A sheepdog is hairy. A peach is hairy (those tiny fuzz-like hairs on the skin). Your uncle might have hairy arms, or you might notice how hairy a tarantula looks up close.

But hairy also means dangerous, scary, or difficult in a way that makes you nervous. When someone describes a hairy situation, they mean something risky or uncertain is happening. A mountain climber might talk about a hairy moment when their rope slipped, or a driver might describe navigating through a sudden snowstorm as pretty hairy.

The connection between these meanings makes sense when you think about how hair stands up on animals (and people) when they're frightened or threatened. That physical reaction to danger gave us this second meaning. When your older sister says her math test was hairy, she's not saying it was covered in fur: she means it was tough and maybe a little scary, full of problems that made her worry she might not do well.