1. A thin wood or metal strip used in building construction
2. A key that is fixed to one of two connected mechanical parts and fits into a keyway in the other; also; a keyway for such a key
3. A function that is defined on an interval, is used to approximate a given function, and is composed of pieces of simple functions defined on subintervals and joined at their endpoints with a suitable degree of smoothness
4. A flexible strip (wood or rubber) used in drawing curved lines.
In computer graphics, a curve calculated by a mathematical function that connects separate points with a high degree of smoothness. See the illustration. See also Bézier curve.