Did you know?

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

rat - 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.

Thesaurus diagram

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.

verb     rat pronunciation in British English
Word Forms
present tense
present participleratting
past tenseratted
past participleratted

phrasal verb

rat on

Word Forms
present tense
I/you/we/theyrat on
he/she/itrats on
present participleratting on
past tenseratted on
past participleratted on
  1. 1
    rat on someone to tell someone in authority about something that someone you know has done wrong
  2. 2
    rat on something British to not do something that you promised to do

    I can’t back someone who rats on his promises.

quiz invitation

gig economy

an employment concept in which people are paid for each specific, short-term task that they do and don't have conventional contracts of employment

BuzzWord Article

Open Dictionary

fake news

a sensational piece of news which does not map to reality, created to attract attention or damage somebody's reputation

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
Macmillan learn live love play