Codimension
Codimension is a term used in a number of algebraic and geometric contexts to indicate the difference between the dimension of certain objects and the dimension of a smaller object contained in it. This rough definition applies to vector spaces (the codimension of the subspace (4, -1, 10) in R^3 is 3 - 1 = 2) and to topological spaces (with respect to the Euclidean topology and the Zariski topology, the codimension of a sphere in R^3 is 3 - 2 = 1).