Our bodies are covered with skin, a layer of tissue that's also humans' largest organ. When you are sick and have a fever, your skin feels warm.
Skin is something we have in common with other vertebrates. The peels of some fruits and vegetables are sometimes called skin too. As a verb, skin means to remove a peel or skin, or to scrape your skin: "If you skateboard in shorts, you're going to skin your knee." If you do something "by the skin of your teeth," you just barely manage it. Skin comes from the Old Norse word skinn, "animal hide."