Main Page | See live article | Alphabetical index Dilation is the act of expanding something. This term is usually used in the context of "dilating the eyes". In mathematics, a dilation is a function f from a metric space into itself that satisfies the identity where d(x,y) is the distance from x to y and r is some real number. A dilation of a Euclidean space is called a similarity. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.