Definition of rat
- a mall rat
a dirty old building infested by rats and mice
I can't believe that rat turned us in to the police!
No one understands why she's with a rat like him.
Every night he goes to work out with the other gym rats.
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rat.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
son of a gun;
The teacher knows what we did, which means that somebody ratted.
: a small animal that has a pointed nose and a long, thin tail
: a person who is not loyal or who cannot be trusted
: a person who is bad or cruel
: to tell someone in authority (such as the police) about something wrong that someone has done : to betray someone ( US )
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