Final answer:
Regular languages are closed under the union operation, which means the union of two regular languages is also a regular language, confirmable by constructing a finite automaton that recognizes the union.
Step-by-step explanation:
Yes, regular languages are closed under the operation of union (reunion).
In other words, if you have two regular languages, their union will also be a regular language.
This is one of the closure properties of regular languages in formal language theory, a subject studied in computer science.
To provide an example, let's say you have two regular languages L1 and L2.
Representing each with their respective finite automata, you can construct a new finite automaton that recognizes L1 ∪ L2 simply by introducing a new start state that non-deterministically transitions to the start states of the automata for L1 and L2.
The resulting automaton will accept a string if it belongs to either L1 or L2, hence recognizing the union of the two languages.