Longman Dictionary of Contemporary English homepage

rat

2 verb
     
rat2 past tense and past participle ratted, present participle ratting [intransitive] informal
1 if someone rats on you, they tell someone in authority about something wrong that you have done [= grass on]
rat on
They'll kill you if they find out you've ratted on them!
2 British English to not do what you had promised to do [= go back on, renege on]
rat on
He accused the government of ratting on its promises to the disabled.

rat somebody ↔ out

if someone rats you out, they are disloyal to you, especially by telling someone in authority about something wrong that you have done:
You can't rat out your teammates.

Dictionary pictures of the day
Do you know what each of these is called?
What is the word for picture 1? What is the word for picture 2? What is the word for picture 3? What is the word for picture 4?
Click on any of the pictures above to find out what it is called.

Explore our topic dictionary