A binary operator representing disjoint union of sets, commonly used in set theory and abstract algebra.
Examples
Disjoint union of sets
A \uplus B = \{(x,0) : x \in A\} \cup \{(x,1) : x \in B\}
Multiple disjoint unions
X = A_1 \uplus A_2 \uplus A_3
Disjoint union of multisets
\{1,1,2\} \uplus \{1,2,2\} = \{1,1,1,2,2,2\}