- any of several long-tailed rodents of the family Muridae, of the genus Rattus and related genera, distinguished from the mouse by being larger.
- any of various similar or related animals.
- Slang. a scoundrel.
- a person who abandons or betrays his or her party or associates, especially in a time of trouble.
- an informer.
- a scab laborer.
- Slang. a person who frequents a specified place: a mall rat; gym rats.
- a pad with tapered ends formerly used in women's hair styles to give the appearance of greater thickness.
- rats, Slang. (an exclamation of disappointment, disgust, or disbelief.)
- to desert one's party or associates, especially in a time of trouble.
- to turn informer; squeal: He ratted on the gang, and the police arrested them.
- to work as a scab.
- to hunt or catch rats.
- to dress (the hair) with or as if with a rat.
- smell a rat, to suspect or surmise treachery; have suspicion: After noting several discrepancies in his client's story, the attorney began to smell a rat.
Origin of rat
Examples from the Web for rat
One rat had once fallen on his head, he said, during a rat raid of a local home.The Crazy Medieval Island of Sark
October 4, 2014
Since rat root comes from a plant that grows on the edge of the lake there are concerns that the plant is carrying toxins.Our Trip to The Climate War's Ground Zero
September 19, 2014
A cabin filled with the Rat Pack and the ladies who loved them.
Not that the Rat Pack party days were completely behind him.
A flea, Xenopsylla cheopis, from an infected little mammal—usually a rat—can hop from the dying rat onto a human and bite it.It’s Not Time to Worry About China’s Plague Just Yet
July 23, 2014
Mr. COX said he could not smelt a pig, but he thought he smelt a rat.
Was the occupant a rat or a skunk, and if so, what was he going to do?A Woman Tenderfoot
Grace Gallatin Seton-Thompson
I suppose I could if I wished; but then one must rat—that's a bore.Night and Morning, Complete
Not a rat could have crawled out since we came, nor could one have gone in.It Happened in Egypt
C. N. Williamson
So, he got the copper and the nails and the pot and the rat that could speak, and the Devil vanished.The Uncommercial Traveller
- any of numerous long-tailed murine rodents, esp of the genus Rattus, that are similar to but larger than mice and are now distributed all over the worldSee also brown rat, black rat
- informal a person who deserts his or her friends or associates, esp in time of trouble
- informal a worker who works during a strike; blackleg; scab
- slang, mainly US an informer; stool pigeon
- informal a despicable person
- smell a rat to detect something suspicious
- (intr usually foll by on) informal
- to divulge secret information (about); betray the trust (of)
- to default (on); abandonhe ratted on the project at the last minute
- to hunt and kill rats
Word Origin and History for rat
late Old English ræt "rat," of uncertain origin. Similar words are found in Celtic (Gaelic radan), Romanic (Italian ratto, Spanish rata, French rat) and Germanic (Old Saxon ratta; Dutch rat; German Ratte, dialectal Ratz; Swedish råtta, Danish rotte) languages, but connection is uncertain and origin unknown. In all this it is very much like cat.
Perhaps from Vulgar Latin *rattus, but Weekley thinks this is of Germanic origin, "the animal having come from the East with the race-migrations" and the word passing thence to the Romanic languages. American Heritage and Tucker connect Old English ræt to Latin rodere and thus PIE *red- "to scrape, scratch, gnaw," source of rodent (q.v.). Klein says there is no such connection and suggests a possible cognate in Greek rhine "file, rasp." Weekley connects them with a question mark and Barnhart writes, "the relationship to each other of the Germanic, Romance, and Celtic words for rat is uncertain." OED says "probable" the rat word spread from Germanic to Romanic, but takes no position on ultimate origin.
RATS. Of these there are the following kinds: a black rat and a grey rat, a py-rat and a cu-rat. ["Dictionary of the Vulgar Tongue," Grose, 1788]
Middle English common form was ratton, from augmented Old French form raton. Sense of "one who abandons his associates" (1620s) is from belief that rats leave a ship about to sink or a house about to fall and led to meaning "traitor, informant" (1902; verb 1910). Interjection rats is American English, 1886. To smell a rat is 1540s; "to be put on the watch by suspicion as the cat by the scent of a rat; to suspect danger" [Johnson]. _____-rat, "person who frequents _____" (in earliest reference dock-rat) is from 1864.
1812, "to desert one's party; 1864 as "to catch rats;" 1921 as "to peach on, inform on, behave dishonestly toward;" from rat (n.). Related: Ratted; ratting.
- Any of various long-tailed rodents of the genus Rattus and related genera, including certain strains used in scientific research and certain species that are vectors for various diseases.
Idioms and Phrases with rat
In addition to the idioms beginning with rat
- rat on
- rat race
- like a drowned rat
- smell a rat