Did you know?

Click any word in a definition or example to find the entry for that word

red line - definition and synonyms


What are red words?

90% of the time, speakers of English use just 7,500 words in speech and writing. These words appear in red, and are graded with stars. One-star words are frequent, two-star words are more frequent, and three-star words are the most frequent.



The thesaurus of synonyms and related words is fully integrated into the dictionary. Click on the thesaurus category heading under the button in an entry to see the synonyms and related words for that meaning.

noun [countable] red line pronunciation in British English /ˌred ˈlaɪn/
Word Forms
singularred line
pluralred lines
  • Facebook
  • Twitter
  1. 1
    a statement, typically by a government, of acts that they regard as unacceptable and will respond to
    The use of chemical weapons during war is a red line issue.
  2. From our crowdsourced Open Dictionary
    a statement, typically by a government, of acts that they regard as unacceptable and will respond to
    Prime Minister Bibi Netanyahu of Israel has been loudly demanding that America publicly draw a “red line” in respect to Iran’s nuclear program that would delineate exactly when the U.S. would launch a strike against Tehran.
    Submitted from United Kingdom on 24/09/2012
Word story
Red line has been used since the 1970s to denote a limit beyond which someone must not go without facing severe consequences. It suggests the idea of a physical boundary marking the limits between acceptable and unacceptable behaviour, and is related to expressions such as ’cross a line’ and ’draw a line in the sand’.


a meal served in the evening which consists of foods traditionally eaten at breakfast

BuzzWord Article

Open Dictionary

troll factory

a company that pays its employees to write online comments in favour or against somebody or something posing as ordinary Internet users

add a word


A must for anyone with an interest in the changing face of language. The Macmillan Dictionary blog explores English as it is spoken around the world today.

global English and language change from our blog