In Unified Modeling Language (UML) 2.5.1, an Element[1] is "a constituent of a model. As such, it has the capability of owning other Elements."[1]
In UML 2.4.1, an element is an abstract class with no superclass.[2] It is used as the superclass or base class, as known by object-oriented programmers, for all the metaclasses in the UML infrastructure library. All other elements in the UML inherit, directly or indirectly from Element. An Element has a derived composition association to itself to support the general capability for elements to own other elements. As such, it has no additional attributes as part of its specification.