containedness

Containedness refers to the state or quality of being contained within a boundary, container, or enclosing set. It describes a relationship in which one thing is entirely inside or included within another. The term is used across disciplines to express notions of inclusion, enclosure, or constraint without implying any particular mechanism of containment.

In mathematics and related fields, containment denotes inclusion. A is contained in B when A ⊆ B; if A ≠ B, A is properly contained in B. This idea extends to topological spaces (subsets with a subspace topology) and to functions (the image is contained in the codomain).

In computer science, containers such as lists, arrays, and maps hold contained elements; containment tests determine whether an element is in a container. In object‑oriented design, containment describes a whole–part relationship where one object includes another as a component.

In linguistics and philosophy, containment relates to part–whole relations (mereology) and semantic hierarchies: hyponymy, where the extension of a term is contained within the extension of a broader term (dog within animal).

In science and engineering, containment refers to physical barriers that confine materials or energy, such as containment structures in nuclear facilities or spill containment. It also covers boundary conditions that restrict a system’s state. Across fields, containedness captures the general idea of one domain being inside or governed by another’s limits.