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

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.
Recent Examples on the Web
Noun
Last year’s report cards famously revealed that the Jacksonville Jaguars had a temporary rat infestation in the locker room, though the team scored highly this year having opened a shiny new training facility in June. George Ramsay, CNN, 29 Feb. 2024 The plane was grounded for three days in the Sri Lankan capital while the aircraft was sprayed with rat poison. Sarah Rumpf-Whitten, Fox News, 28 Feb. 2024 Like Winston Smith’s humiliation at the end of George Orwell’s 1984 when regime torturer O’Brien fits a rat cage to the protagonist’s face, Kennedy cried, Do it to the Palestinians! Scott Horton, Orange County Register, 25 Feb. 2024 The story goes that during the plagues that swept across Europe in the Middle Ages, Kotor brought a handful of cats into the walled city to kill the infected rats. Meagan Drillinger, Travel + Leisure, 24 Feb. 2024 In addition to the problems at the women’s jail, the oversight report also raised concerns about an ongoing rat problem at Men’s Central Jail, a decaying facility built downtown in the 1960s, which the county has been aiming to close for several years. Keri Blakinger, Los Angeles Times, 22 Feb. 2024 There are 12 different animals in the race: rat, ox, tiger, rabbit, dragon, snake, horse, goat, monkey, rooster, dog and pig. Julie Lin, Condé Nast Traveler, 16 Feb. 2024 Zodiac animals are rat, ox, tiger, rabbit, dragon, snake, horse, goat, monkey, rooster, dog and pig. Detroit Free Press, 23 Feb. 2024 To mirror Christopher’s fast-calculating brain, Lapp’s production is an intentionally busy one in constant motion, with two video screens, live camera feeds, and actors playing everything from a pet rat to an ATM to an electric blender. Pam Kragen, San Diego Union-Tribune, 19 Feb. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'rat.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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 19 Mar. 2024.

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

rat

noun
: 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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