Meanings
nounnegative lookahead (countable and uncountable, plural negative lookaheads)
plural negative lookaheads
- countableuncountableregular expressionsThe analysis of the subsequent characters absence before the regular expression is matched (symbol: ?!).
Negative lookahead works just like positive lookahead, except that whereas positive lookahead matches when the regex inside the lookahead matches, negative lookahead matches when the regex inside the lookahead failed to match.
2012 August, Jan Goyvaerts, Steven Levithan, Regular Expressions Cookbook
Origin
Cite this entry
APA
negative lookahead. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/negative%20lookahead
MLA
“negative lookahead.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/negative%20lookahead. Accessed November 4, 2026.
Chicago
WatkinsX Dictionary, s.v. “negative lookahead,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/negative%20lookahead.
Source: negative lookahead on Wiktionary, CC BY-SA 4.0.