An sich is an expression borrowed from German language. Its translation is "as such" or "in itself".

Despite having an adequate translation, the term is used in philosophical contexts as a professional jargon to avoid ambiguity of the general language. The expression "something an sich" means that the discussed "something" is considered only in relation of its intrinsic properties, not related to its surroundings or context.

The expression "an sich" entered many languages after the famous German philosopher Immanuel Kant introduced his notion of Ding an sich (thing-in-itself), however in a somewhat mutated usage: Kant's notion indeed refers to the intrinsic properties of a "thing", but to the ones which are inherently beyond the human cognition.