---
tag: NMN1NEZS04
kind: concept
name: Disjoint union
aliases: [disjoint-unions]
sources:
  - wikipedia: en:188946@r1335705780
    locator: Disjoint union
    note: adopted
    mention: wikipedia://en/188946
    sections: [Summary]
same_as:
  wikidata: Q842620
  wikipedia: Disjoint union
inventory: [M24H9HFD38]
---

## Summary

In mathematics, the **disjoint union** (or **discriminated union**) $A \sqcup B$ of the sets $A$ and $B$ is the set formed from the elements of $A$ and $B$ labelled (indexed) with the name of the set from which they come. So, an element belonging to both $A$ and $B$ appears twice in the disjoint union, with two different labels.