regular language
Technical term in formal language theory and computer science. A regular language is a formal language that can be expressed by a regular expression or recognized by a finite automaton.
Regular languages are the class of languages that can be accepted by finite automata.
Please explain the regular language represented by this regular expression.
正規表現 (regular expression) is a notation for describing regular languages, while 正規言語 is the set of strings itself.
形式言語 (formal language) is a broader category; regular languages are a specific type of formal language.
Compound of 正規 (regular, normal) and 言語 (language), calque of English 'regular language'.