A sleeve is the part of a shirt, jacket, or other garment that covers your arm. Sleeves come in different lengths: short sleeves end above your elbow, long sleeves reach your wrist, and three-quarter sleeves stop somewhere in between. Some formal shirts have sleeves with buttons at the cuffs, while T-shirts have simple sleeves with no fasteners.

The word also appears in several common expressions. When someone has a trick up their sleeve, they're keeping a secret plan or idea ready for the right moment, like a magician hiding a card in their sleeve. If you wear your heart on your sleeve, you show your emotions openly instead of hiding how you feel. And when you roll up your sleeves, you're preparing to work hard on something, literally pushing your sleeves up your arms so they don't get in the way.

A sleeve can also mean a protective cover, like the cardboard sleeve that protects a vinyl record or the plastic sleeve that holds documents in a binder.