wrapper
A piece of material that covers and protects something.
A wrapper is a piece of material that covers or encloses something to protect it or hold it together. When you open a candy bar, you tear off the paper or foil wrapper before eating the chocolate inside. The wrapper kept the candy clean and fresh until you were ready to enjoy it.
Wrappers serve different purposes depending on what they cover. A plastic wrapper protects a new book from getting damaged during shipping. The colorful paper wrapper on a crayon keeps your fingers clean while you draw and shows what color it is. A tortilla acts as an edible wrapper when it holds beans, cheese, and other ingredients in a burrito.
In computer programming, a wrapper is a section of code that surrounds another piece of code to make it easier to use or to add extra features. It “wraps around” existing code the same way a blanket wraps around you.
When you wrap a gift in decorative paper, you're creating a wrapper that conceals the present inside and builds excitement before you open it.