Word.ws English Dictionary

negative lookahead

negative lookahead noun: the analysis of the subsequent characters absence before the regular expression is matched (symbol: ?!).

Noun

negative lookahead (countable and uncountable, plural negative lookaheads)

  1. (regular expressions) The 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

Forms of negative lookahead

pluralnegative lookaheads

Origin of negative lookahead

From negative + lookahead.

Questions about negative lookahead

What does negative lookahead mean?
Negative lookahead means the analysis of the subsequent characters absence before the regular expression is matched (symbol: ?!).
What part of speech is negative lookahead?
Negative lookahead is a noun.
What is the plural of negative lookahead?
The plural of negative lookahead is negative lookaheads.

Words near negative lookahead in the dictionary

  1. negative income tax
  2. negative income taxes
  3. negative indexing
  4. negative interest
  5. negative logic
  6. negative lookahead
  7. negative lookaheads
  8. negative lookaround
  9. negative lookbehind
  10. negative lookbehinds
  11. negative nancies

Source and license

Adapted from Wiktionary: negative lookahead (page history and authors). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

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