rat

1 of 2

noun

1
a
: any of numerous rodents (Rattus and related genera) differing from the related mice especially by considerably larger size
b
: any of various similar rodents
2
: a contemptible person: such as
a
: one who betrays or deserts friends or associates
3
: a pad over which a woman's hair is arranged
4
: a person who spends much time in a specified place
a mall rat
ratlike adjective

rat

2 of 2

verb

ratted; ratting

intransitive verb

1
: to betray, desert, or inform on one's associates
usually used with on
2
: to catch or hunt rats
3
: to work as a scab

transitive verb

1
: to give (hair) the effect of greater quantity (as by use of a rat)
2
: to inform on : turn in
usually used with out
ratted out his accomplice

Example Sentences

Noun 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. Verb The teacher knows what we did, which means that somebody ratted.
Recent Examples on the Web
Noun
Now add to that list a brick from Osama bin Laden's final hideout, and the AK-47 found by his side; flight suits worn by clandestine surveillance pilots; and a taxidermied rat, used by spies to hide messages during the Cold War. CBS News, 2 Oct. 2022 The rat-a-tat, scherzando energy of the opening bars is sustained throughout the first act, which takes us up to Antony’s defeat at the Battle of Actium. Alex Ross, The New Yorker, 26 Sep. 2022 Like his peers, Locane details gangland tales over unforgiving bass wallop and rat-a-tat percussion that are punctuated by mournful melodies and cinematic samples. Chris Kelly, Washington Post, 6 July 2022 That rat-a-tat racket was a part of the CrossRoads Missions/Habitat for Humanity house construction project. Jeff Vorva, Chicago Tribune, 6 June 2022 His buddies knew his talents for table-to-table rat-a-tat, and urged him to make a tape. New York Times, 23 May 2022 Redtro follows in hot pursuit as the rat-a-tat from the guns gets louder. Lynsey Weatherspoon/redux For Cnn, CNN, 7 May 2022 Chicago held onto its claim as the nation's rat capital for the eighth consecutive year, Orkin said. Orlando Mayorquin, USA TODAY, 25 Oct. 2022 According to New York City Councilmember Scott Abreu, the city has seen a 71% increase in rat sightings since 2020. Simrin Singh, CBS News, 19 Oct. 2022 See More

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.

Word History

Etymology

Noun

Middle English rat, ratte, going back to Old English ræt (attested once), akin to Old Saxon ratta "rat," Middle Dutch ratte, rotte, Old High German ratta, radda, ratza (feminine weak nouns), also Old High German rato (masculine weak noun), probably going back to an ablauting paradigm *raþō (nominative), *rattaz/*ruttaz (genitive), *radeni/*rudeni (dative), going back to earlier *(H)rót-ōn, *(H)rt-n-ós, *(H)rt-én-i, of uncertain origin

Note: The origin of the etymon beyond Germanic is obscure. Regionally in German Ratz or Ratze are applied to other animals (as the dormouse and the polecat); if these senses are old, the application of the etymon to rats (Rattus rattus, Rattus norvegicus) may be secondary. Note that if the base is pre-Germanic *rat-, there is no connection to either Latin rōdere "gnaw, nibble, eat away" (see rodent) or rādere "scrape, shave" (see rase), as has often been assumed.

First Known Use

Noun

before the 12th century, in the meaning defined at sense 1a

Verb

1812, in the meaning defined at intransitive sense 1

Time Traveler
The first known use of rat was before the 12th century

Dictionary Entries Near rat

Cite this Entry

“Rat.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rat. Accessed 26 Nov. 2022.

Kids Definition

rat 1 of 2

noun

1
: any of various rodents that have brown, black, white, or grayish fur and a long usually nearly hairless tail and that look like but are larger than the related mice
2
: a person who betrays friends
3
: a person who spends much time in a specified place
a mall rat
ratlike adjective

rat

2 of 2

verb

ratted; ratting
1
: to betray, desert, or inform on one's friends
didn't rat on us
ratted them out
2
: to catch or hunt rats

Medical Definition

: any of the numerous rodents (family Muridae) of Rattus and related genera that differ from the murid mice by their usually considerably larger size and by features of the teeth and other structures and that include forms (as the brown rat, the black rat, and the roof rat) which live in and about human habitations and in ships, have become naturalized by commerce in most parts of the world, and are destructive pests consuming or destroying vast quantities of food and other goods and acting as vectors of various diseases (as bubonic plague)

More from Merriam-Webster on rat

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