What does "backreference" mean?

An item in a regular expression equivalent to the text matched by an earlier pattern in the expression.

Backreference

noun, verb

noun, verb ·Rare ·Advanced level

Noun

1
An item in a regular expression equivalent to the text matched by an earlier pattern in the expression.
"The third part of the regular expression, \1, is the backreference and tells ColdFusion to refer back to the first subexpression[…]"

Verb

1
To access (the text matched by an earlier pattern in a regular expression). transitive
"By wrapping it in parentheses, the attributes can be reused by backreferencing this part of the pattern[…]"

"The third part of the regular expression, \1, is the backreference and tells ColdFusion to refer back to the first subexpression[…]"

From back + reference.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.