Definition of rat in US English:

rat

nounPlural rats

  • 1A rodent that resembles a large mouse, typically having a pointed snout and a long, sparsely haired tail. Some kinds have become cosmopolitan and are sometimes responsible for transmitting diseases.

    Family Muridae: many genera, including Rattus (the Old World rats), and several hundred species

    • ‘Control lung tissue was also obtained from adult male rats.’
    • ‘Wistar albino rats were divided into five groups.’
    • ‘Cane rats should not be confused with domestic rodents such as rats and mice which can be disease-carrying vermin.’
    • ‘Despite the situation, they're not lab rats in a cage; they're fellow human beings.’
    • ‘Adult male albino rats were housed in the controlled temperature and photoperiod.’
    • ‘It turns out that mice and rats and some other rodents have hearing which looks very similar to ours.’
    • ‘Luckily we didn't see any dead rats.’
    • ‘One rat's nest can turn into a colony of 50 rats in six months.’
    • ‘Inside his Manhattan brownstone lurks something even more terrifying than his business associates: a giant sewer rat.’
    • ‘What's the difference between a water vole and a rat?’
    • ‘Pigeons cooed from the rooftops of buildings, and rats scurried along the floor.’
    • ‘The number of genetic differences between humans and chimps is ten times smaller than that between mice and rats.’
    • ‘One resident said she has seen rats scurrying out to snatch discarded pieces of bread in broad daylight.’
    • ‘He notes that wild cats may have been drawn to settlements where grain stores attracted rats and mice.’
    • ‘Admittedly some of the rodents that possess the ability, such as rats and mice, are almost completely nocturnal.’
    • ‘Most people are familiar with mice, rats, hamsters, and guinea pigs, which are commonly kept as pets.’
    • ‘Up until 1987 this kind of experiment had only done in rodents, rats and mice, and in lower organisms.’
    • ‘In one study, researchers exposed laboratory rats to a toxin that is known to cause Parkinson's disease.’
    • ‘We used 18 male adult hooded rats that were maintained under the same conditions as those in Experiment 1.’
    • ‘Bodies start to smell like dead rats if you leave them in one place too long.’
  • 2informal A person regarded as despicable, especially a man who has been deceitful or disloyal.

    • ‘Most especially, every jerk bureaucrat and greedy welfare rat (particularly the rich ones) with a hand in the public till gets to vote.’
    • ‘You know every rat, snitch and scoundrel on this island, and between them they know everything shady that transpires.’
    • ‘Congratulations to Bob, you rat, despite not, building in A01 and NMRing three times.’
    • ‘She's doing it all for her own self pleasure, that rat!’
    • ‘Here was the building that housed the penthouse where Nick had lived, and where she'd met his street rat friend that actually caught her heart for a time.’
    • ‘If you're out there you rat, I finally caught on and I want my money back.’
    • ‘We went back to the set and I watched the Falcon escape from bondage and alert the cops to where the crime boss and his rats were hiding out.’
    • ‘He then recognised the ship approaching them ‘I should've known that rat would be here.’’
    • ‘Pretty soon, the hooligans, graffiti artists, drug addicts, pushers - and rats - take over.’
    • ‘Even Thatcher herself wouldn't have dreamed that the king rat builders would so effectively take over an entire country's development with no real opposition.’
    • ‘I spat at him, ‘I hope your wife finds out what a cheating, lying rat you really are and you get all that you deserve!’’
    • ‘He, who's a braggart and a drunk and a rat and a scoundrel, at his death bed, says, I find Christ.’
    • ‘The good news is that his adviser, that rat Fred Tough, has had to go with him.’
    • ‘He was so unworthy, a lowly thief, a rat, unfit to breathe Her Majesty's air.’
    • ‘‘For your information this little rat insulted me’ Debbie huffed sticking her chin up snobbishly.’
    • ‘How can you make a philandering love cheat, who works his way through a family of sisters, anything but a rogue and a rat?’
    scoundrel, wretch, rogue
    View synonyms
    1. 2.1 An informer.
      • ‘He was supposedly the rat who betrayed the Gibraltar Three, the Eksund gun runners and the IRA men assassinated at Loughgall.’
      • ‘I go by beeper now because there's too many rats [informants] on the street.’
      • ‘Nadeau, as his name would indicate, has no love for informants and rejects the notion that he was a rat.’
      • ‘I would ask you again whether the killing of a rat is murder?’
      • ‘It's different when Right Wingers want to crush free speech and create a police state environment of informers and rats in a house of worship.’
      • ‘Mr. Ken told me that the rat was an informant for the enemy.’
      • ‘She may not be a barracks rat, but she's not too far off.’
      • ‘It is funny to see that the rats at various British intelligence agencies are already trying to avoid the blame for the lies told to the British people by Blair.’
      • ‘These rats do whistle an alarm, but we didn't hear it.’
      informer, betrayer, stool pigeon
      View synonyms
  • 3North American informal with modifier A person who is associated with or frequents a specified place.

    ‘LA mall rats’
    ‘you and the rest of the tavern rats will have to find a new hangout’
    • ‘Shouldn't we at least insist she sells some records like, this decade, before she gets any more coverage for her sex romp/love rat lifestyle?’
    • ‘Cardboard cutouts of the love rat MP are proliferating.’
    • ‘Mali, while seeming sophisticated, wanders in and out of ghetto rat behavior, especially when it comes to her man, Tad Honeywell.’
    • ‘Peralta ripping in back of Mar Vista Elementary School - the first playground he was officially kicked out of as a young skate rat.’
    • ‘The promo challenges non-gym rats to get in shape during a 30-day period.’
    • ‘There's nowhere else I'd rather be right now - on a trip in South Africa with a good crew and having fun, skating everyday, and doing a real skate rat tour.’
    • ‘And the bag boys all seem to be happy, happy surf rats, with funny haircuts and pretty smiles.’
    • ‘You had your hardcore kids, punks, and skate rats big on yelling and beer, skeptical of synths and Englishmen.’
    • ‘Some eighteen year old street rat from Paris, France… I wanted him so badly in my world of glitz and glamour… what am I saying?’
    • ‘Rhyming, however, is the favourite sound effect of slang, as in boob tube television, frat rat member of a US college fraternity.’
    • ‘Too many effective leaders have behaved badly in their love lives to make credible the claim that being a love rat is incompatible with being a good president.’
    • ‘Contrary to popular opinion, in general they are not just attracting low lifes, low-end demographic users, gym rats and the like.’
    • ‘The strike taught these wharf rats about power - that working people could get it, and wield it with devastating effect, if they understood that the world depended on them.’
    • ‘I'm the one who always has to get out front and say ‘no’, and explain, and be the lousy wharf rat because they think I'm running a fraud.’
    • ‘I'm a 46-year-old Ohio river rat who's gone there half a dozen times to mountain bike and ski.’
    • ‘I believe in spirits - I think we all do - and I don't think this woman who lived in this house was too happy when skate rats all showed up to ride her pool.’
    • ‘That bum sitting on a heating grate, smelling like a wharf rat?’
    • ‘THERE ARE DOZENS OF dilemmas facing the average gym rat every time he steps foot in the weight room.’
    • ‘He fought a handful of amateur and charity fights, earning him some credit as a middle-aged gym rat.’
    • ‘After spending a long, hard winter as a gym rat shut-in, you're probably hot to trot outdoors.’
    • ‘At the first, it was decided to axe three popular characters - love rat doctor Matt Ramsden, his teacher wife Charlie, and shopworker Bobbi Lewis.’
    • ‘Then or course there's the biggest closet rat of all, me.’
    • ‘Gym rats from the east to the west coast prefer tank tops because they allow for complete range of motion and allow gym buffs to admire their flexed muscles at all times.’
  • 4US A pad used to give shape and fullness to a woman's hair.

exclamation

rats
informal
  • Used to express mild annoyance or irritation.

    • ‘I just came upstairs to check the price of something on eBay (under $10, rats!) and saw the clock.’
    • ‘Divisions were actually for sale at Behnke, a nursery local to me and I didn't know it - rats!’
    damn, damnation, blast, hell, heck, gordon bennett
    View synonyms

verbrats, ratted, ratting

[no object]
  • 1usually as noun ratting(of a person, dog, or cat) hunt or kill rats.

    • ‘The Shar Pei still exhibits these herding and ratting instincts.’
    • ‘The Border is a hunter, earth dog, show dog and obedience dog, a whiz at agility trials, ratting in the barns and tracking.’
    • ‘We reckon the dog might be a bit handy at ratting or hare coursing.’
    • ‘In another era, perhaps he and his mates would simply have gone out poaching or ratting, grumbling about bloody women along the way.’
    • ‘The dog is immensely pleased with herself; she is heavily pregnant and ratting was evidently a highly desirable break in just sitting in a corner of the kitchen day after day inflating and waiting for the puppies.’
    • ‘The Giant Schnauzer's original job was ratting.’
  • 2informal Desert one's party, side, or cause.

    • ‘Shortly afterwards, getting into his car, he was called by name and, when he turned, was shot through the forehead by a fellow extremist who suspected he had ratted.’
    • ‘He always said that he wouldn't tell on me but he always ended up ratting.’
    • ‘The other men don't shoot the soldier who ratted, however.’
    • ‘Talk of Bob Sercombe ratting is just that, his self-preservation demands him staying where he is.’
    • ‘That's especially true if the White House really did call six or more reporters with this leak, since that means that if the names come out there's no way of knowing which reporter ratted.’
    • ‘Anna hit me in the arm a little mad that I had ratted so easily.’
    • ‘Here's an interesting one about sneaky civil servants using their access to databases to rat to the press on Lotto winners.’
    • ‘Ratting on your mates is regarded as a sin in Australia, but if your mates have done the wrong thing and the ratting merely comprises a truthful public disclosure of some relevant information, then it should be encouraged.’
    • ‘The Stability Pact was to have kept the currency health, but it became inconvenient for France, which ratted, followed by Germany, France, Italy, Holland, and Greece.’
    • ‘Yeah, I'll bet she's just the type to rat, eh, Eddie?’
    • ‘And it's equally unsurprising that he would deny it when one of those Liberal insiders ratted and went public.’
    • ‘Unfortunately, after republicans ratted and robbed and killed and the two governments failed to punish them with more than the odd ‘tut, tut’ unionists decided they'd been sold a pup.’
  • 3US Give (hair) shape or fullness with a rat.

    • ‘She's got long black hair, ratted and dry, and it hangs down over her shoulders like a fern that hasn't been watered in weeks.’
    • ‘Her ponytail was ratted and her bangs were sticking up all over while her braids were perfectly fine as they always were.’
    • ‘All he knew was the sad grey eyes of the man, and his long ratted graying hair.’
    • ‘There was Stacey in her big girl bra, ratted out hair and adult acne.’
    • ‘Why does a girl like Gwynie have to go and rat up her hair like that?’

Phrasal Verbs

  • rat on

    • 1Inform on (someone) to a person in a position of authority.

      ‘I never thought Stash would rat on me’
      ‘men will literally choose death over ratting out another prisoner’
      • ‘‘Thanks,’ I said once we were out of the office, ‘for not ratting me out.’’
      • ‘You ever considered ratting her out to your parents?’
      • ‘I like her and she lets me get out of class when I need to without ratting me out.’
      • ‘He believes (correctly, as it turns out) that a fellow officer has been ratting him out to the precinct's captain.’
      • ‘Words and titles are about to become very important as people figure out which one of Cheney's goons ratted her out.’
      • ‘‘I don't think you should rat her out, but let her know you saw her cheating and that it could get her in a lot of trouble,’ suggests Lindsay.’
      • ‘Christy was going to pay dearly for ratting her out.’
      • ‘I hadn't planned on ratting Ryan out anyway, but his response had taken me by surprise.’
      • ‘It would perhaps be different if the only two alternatives were ratting him out or deceiving her employer.’
      • ‘The last thing that I need is Zach ratting me out to my parents.’
      inform against, inform on, betray, be disloyal to, be unfaithful to, break one's promise to, break faith with, sell out, stab someone in the back
      View synonyms
      1. 1.1Break (an agreement or promise)
        ‘he accused the government of ratting on an earlier pledge’
        • ‘Mind you, I had to do a bit of fast footwork to get the Foreign Office to rat on that fisheries deal that Jack Straw had done with Alex Salmond.’
        • ‘Allies of the Chancellor accused Downing Street of ratting on a deal struck between the two men to maintain a united front when dealing with Britain's pensions time bomb.’
        • ‘It is about the government ratting on an undertaking.’
        • ‘He ratted on his promise to take me with him - saying that there would be questions in the parliament if he spent too much money.’
        • ‘Whatever the cause, France ratted on his agreement, retaking Brest by force.’
        • ‘If we believe Gordon's account, as relayed through Robert Peston, Blair ratted on a promise to go by November of last year.’
        • ‘President George Bush has ratted on the US commitment to reduce the pollution that is causing climate chaos across the globe.’
        • ‘The press have also ratted on virtually every ‘deal’ they've ever entered into concerning a bit of privacy for William and Harry.’
        break, renege on, go back on, back out of, default on, welsh on
        View synonyms

Origin

Old English ræt, probably of Romance origin; reinforced in Middle English by Old French rat. The verb dates from the early 19th century.

Pronunciation

rat

/rat//ræt/