regular expression
compound.compound. a special sequence of characters that helps you find or change specific patterns of text in a computer file. You use it to search for things like email addresses or phone numbers without typing every single one.
compound. a sequence of characters that defines a search pattern, primarily used for string matching and manipulation in programming and text processing. Often abbreviated as 'regex' or 'regexp'.
I used a regular expression to find all the dates in the document.
The developer wrote a regular expression to ensure that every user password contained at least one capital letter and one number.
By implementing a complex regular expression, the script was able to parse thousands of unstructured log files and extract specific error codes for the final report.
The term was coined by the American mathematician Stephen Cole Kleene in 1951 to describe the sets of strings generated by his formal notation for finite automata.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Often functions as the direct object of verbs like 'write', 'use', or 'match'.
Last updated July 22, 2026