any of numerous long-tailed murine rodents, esp of the genus Rattus, that are similar to but larger than mice and are now distributed all over the world
See also brown rat, black rat
2. informal
a person who deserts his or her friends or associates, esp in time of trouble
3. informal
a worker who works during a strike; blackleg; scab
4. slang, mainly US
an informer; stool pigeon
5. informal
a despicable person
6. smell a rat
verbWord forms: rats, ratting or ratted
7. (intransitive; usually foll byon) informal
a.
to divulge secret information (about); betray the trust (of)
b.
to default (on); abandon
he ratted on the project at the last minute
8. (intransitive)
to hunt and kill rats
Derived forms
ratlike (ˈratˌlike)
adjective
Word origin
Old English rætt; related to Old Saxon ratta, Old High German rato
Examples of 'ratting' in a sentence
ratting
Rhonda was committing the sin of sins: she was ratting on a fellow crasher.
Smith, Evelyn E MISS MELVILLE REGRETS
This time there can be no ratting, no halfhearted buying off.
Times, Sunday Times (2014)
Such ratting is no more noble than when politicians snitch on political rivals.
Times, Sunday Times (2007)
Such ratting is often justified by the pious sentiment that the ends justify the means.