# Flatness (mathematics)

In mathematics, the **flatness** (symbol: **⏥**) of a surface is the degree to which it approximates a mathematical plane. The term is often generalized for higher-dimensional manifolds to describe the degree to which they approximate the Euclidean space of the same dimensionality. (See *curvature*.)[1]

**Flatness** in homological algebra and algebraic geometry means, of an object in an abelian category, that is an exact functor. See flat module or, for more generality, flat morphism.[2]