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 But the rat, Remy, helps Linguini save face by hiding in the young man’s hat and puppeteering his hands, essentially, by pulling on his hair. Alex Kane, USA TODAY, "How to watch Ratatouille," 12 Nov. 2019 And, like humans, the rats knew where to find the sweetest, fattiest, tastiest part of the cookie. Jeffrey Kluger, Time, "Food Addictions Are Real Addictions—And More And More People Are Getting Hooked," 6 Nov. 2019 Examples of the island rule include extinct donkey-sized hippos in Cyprus and the giant rats that were once found in the Caribbean and huge insects that are found in New Zealand. Fox News, "Prehistoric 'hobbit' mystery may have been solved," 4 Nov. 2019 The rats climbed into what is essentially a plastic container on wheels. Wired, "These Rats Drive Tiny Cars—for Science," 1 Nov. 2019 Palm trees replaced the ferns and 200,000 years after the impact, mammal diversity spiked again and the rat-like mammals reached the size of a beaver. Ashley Strickland, CNN, "New fossil treasure trove shows what happened for a million years after the dinosaurs went extinct," 24 Oct. 2019 Instead, the rats concerned acted normally until given their preadolescence doses of THC. The Economist, "In rats, cannabis during pregnancy rewires the brains of offspring," 19 Oct. 2019 One primary reason for surprise is the complexity of the game the rats were playing. Francisco Luongo, Scientific American, "Play May Be a Deeper Part of Human Nature Than We Thought," 8 Oct. 2019 DANCE Templeton, the rat from the animated children’s movie Charlotte’s Web, had the right idea -- a fair, err festival, is a veritable smorgasbord of food. Brittany Gaston, Billboard, "A Definitive Ranking of the Tomorrowland 2019 Food Options," 25 July 2019

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

19 Nov 2019

Cite this Entry

“Rat.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/ratted. Accessed 22 November 2019.

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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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