rat

noun
\ ˈrat How to pronounce rat (audio) \

Definition of rat

 (Entry 1 of 2)

1a : 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

rat

verb
ratted; ratting

Definition of rat (Entry 2 of 2)

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 outratted out his accomplice

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Other Words from rat

Noun

ratlike \ ˈrat-​ˌlīk How to pronounce ratlike (audio) \ adjective

Examples of rat in a Sentence

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.
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Recent Examples on the Web: Noun Cole acts as the guardian of the park’s animals, from the garbage rats to Bitsy’s lonely shih tzu-doodle, Shampagne. Kristen Baldwin, EW.com, "Central Park will make your heart sing: Review," 15 May 2020 The rat stood frozen in the corner, but Haydee ignored her new roommate for several minutes. Carl Zimmer, New York Times, "Eat Rat, Make New Body: Easy Stuff for Pythons," 12 May 2020 And so did the viruses rats carry, along with the chances those viruses would jump to people. Abrahm Lustgarten, ProPublica, "How Climate Change Is Contributing to Skyrocketing Rates of Infectious Disease," 7 May 2020 Pale, wrinkled, and hairless, the naked mole-rat looks more like a toothy, undercooked sausage than a paragon of mammalian health. Katherine J. Wu, Smithsonian Magazine, "Naked Mole-Rats Bathe Their Bodies in Carbon Dioxide to Prevent Seizures," 4 May 2020 Infection spread easily because the rats were drawn to human activity, especially the food supplies kept in barns, mills, and homes. National Geographic, "Indeed, historians have argued that the Black Death paved the way for a new wave of opportunity, creativity, and wealth from which would flourish the art, culture, and ideas of the Renaissance, and the beginnings of a recognizably modern Europe.," 23 Apr. 2020 In the sewers and rivulets along the streets in the city of masks the rats ride in masks like passengers in boats crossing the Lethe. Daniel Torday, Wired, "Short Fiction: ‘Indivisible City’ by Daniel Torday," 3 Apr. 2020 There are many signs of the impending crisis, the dead rats in factories, warehouses, and apartment buildings. Siddhartha Deb, The New Republic, "The Pandemic Imagination," 16 Mar. 2020 This is why a reliance on animal testing has become such an embedded part of human culture: Animals like the generic lab rat are the only complete systems on which drugs may be tested. Courtney Linder, Popular Mechanics, "These Impossibly Tiny Organs Could Finally End Animal Testing," 9 Mar. 2020

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.

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First Known Use of rat

Noun

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

Verb

1812, in the meaning defined at intransitive sense 1

History and Etymology for rat

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.

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Time Traveler for rat

Time Traveler

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

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Statistics for rat

Last Updated

20 May 2020

Cite this Entry

“Rat.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rat. Accessed 30 May. 2020.

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More Definitions for rat

rat

noun
How to pronounce rat (audio)

English Language Learners Definition of rat

 (Entry 1 of 2)

: 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

rat

verb

English Language Learners Definition of rat (Entry 2 of 2)

informal : to tell someone in authority (such as the police) about something wrong that someone has done : to betray someone

rat

noun
\ ˈrat How to pronounce rat (audio) \

Kids Definition of rat

 (Entry 1 of 2)

1 : a gnawing animal with brown, black, white, or grayish fur that looks like but is larger than a mouse
2 : a person who betrays friends

rat

verb
ratted; ratting

Kids Definition of rat (Entry 2 of 2)

: to betray a friend

rat

noun
\ ˈrat How to pronounce rat (audio) \

Medical Definition of rat

: 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)

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More from Merriam-Webster on rat

Thesaurus: All synonyms and antonyms for rat

Rhyming Dictionary: Words that rhyme with rat

Spanish Central: Translation of rat

Nglish: Translation of rat for Spanish Speakers

Britannica English: Translation of rat for Arabic Speakers

Britannica.com: Encyclopedia article about rat

Comments on rat

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