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 out ratted out his accomplice

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Other Words from rat

Noun

ratlike \ ˈrat-​ˌlīk How to pronounce rat (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 Built like a rat’s maze, Icebox’s spate of angles and unusual elevation ranges — both experimental points of interest for Riot’s maps team — rubbed some players the wrong way. Mikhail Klimentov, Washington Post, "Here’s how Breeze, ‘Valorant’s’ newest map, was built," 26 Apr. 2021 Already a legendary gym rat, Scalia worked extra hard last summer to be in her best shape. Kent Youngblood, Star Tribune, "Special bond links Sara Scalia and Gophers coach Lindsay Whalen," 13 Feb. 2021 In 2017, researchers reported growing pancreases from mouse stem cells inserted into rat embryos. Mitch Leslie, Science | AAAS, "Lab-grown embryos mix human and monkey cells for the first time," 15 Apr. 2021 The TikTok Musical, which Mertzlufft co-created after teacher Emily Jacobsen’s ode to the Pixar rat went viral. Angela Watercutter, Wired, "TikTok Duets Are Reviving the Exquisite Corpse," 12 Apr. 2021 As the New Yorkers will tell you: Never pick up a can of pop without assuming a rat peed on it. Star Tribune, "Lileks: Will we ever get over our pandemic cleaning fetish?," 9 Apr. 2021 First-generation rat poisons worked in a similar fashion but were less deadly, reports Molly Taft for Gizmodo. Alex Fox, Smithsonian Magazine, "Study Finds Rat Poison in Dead Eagles from Across the U.S.," 8 Apr. 2021 And Eastern Standard’s once-lively patio is dark, occupied by weedy planters and a jumbo-size rat trap. BostonGlobe.com, "For Kenmore Square, does the end of an era mean a promising future?," 3 Apr. 2021 In my experience, no one gives a rat’s about the Syrians (except the Syrians). Jay Nordlinger, National Review, "Living in the White House, &c.," 2 Apr. 2021

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

1 May 2021

Cite this Entry

“Rat.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rat. Accessed 9 May. 2021.

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More Definitions for rat

rat

noun

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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Comments on rat

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