A fox is a small, dog-like wild animal with pointed ears and nose, and a thick tail. A red fox has dark front legs that look like little opera gloves. They’re sneaky, so a fox can also be a tricky person.
There are different kinds of foxes, but they all have a reputation for sneaking around and stealing stuff. Because they’re known for being wily and smart, you can use the word fox to describe someone who's sly: "That old fox always manages to get other people to buy his lunch." Colloquially, a fox is also an attractive person. They say don’t let a fox guard the henhouse, even if the fox is really good looking.