rat

[ rat ]

noun

1. any of several long-tailed rodents of the family Muridae, of the genus Rattus and related genera, distinguished from the mouse by being larger.
2. any of various mammals similar to or related to the long-tailed rodents of the genus Rattus.
3. Slang. a scoundrel.
4. Slang.
   1. a person who abandons or betrays their party or associates, especially in a time of trouble.
   2. an informer.
   3. a scab laborer.
5. Slang. a person who frequents a specified place: gym rats.

   a mall rat;

   gym rats.

6. a pad with tapered ends formerly used in women's hairstyles to give the appearance of greater thickness.

interjection

1. rats, Slang. (an exclamation of disappointment, disgust, or disbelief.)

verb (used without object)

, rat·ted, rat·ting.

1. Slang.
   1. to desert one's party or associates, especially in a time of trouble.
   2. to turn informer; squeal:

      He ratted on the gang, and the police arrested them.

   3. to work as a scab.
2. to hunt or catch rats.

verb (used with object)

, rat·ted, rat·ting.

1. to make (the hair) appear thicker by use of a small pad of material or by teasing.

verb phrase

1. Slang. to inform on:

   He ratted out his partners in exchange for a lighter sentence.

rat

/ ræt /

noun

1. 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 world See also brown rat black rat
2. informal.
   a person who deserts his or her friends or associates, esp in time of trouble
3. informal.
   a worker who works during a strike; blackleg; scab
4. slang.
   an informer; stool pigeon
5. informal.
   a despicable person
6. smell a rat
   to detect something suspicious

verb

1. informal.
   intrusually foll byon
   1. to divulge secret information (about); betray the trust (of)
   2. to default (on); abandon

      he ratted on the project at the last minute

2. to hunt and kill rats

Derived Forms

• ˈratˌlike, adjective

Other Words From

• rat·like adjective

Word History and Origins

Origin of rat¹

First recorded before 1000; Middle English rat(t)te, Old English ræt; cognate with Dutch rat, German Ratz, Ratte

Word History and Origins

Origin of rat¹

Old English rætt ; related to Old Saxon ratta , Old High German rato

Idioms and Phrases

Idioms

1. 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.

More idioms and phrases containing rat

• like a drowned rat
• smell a rat

Example Sentences

"To be specific, nitration happens on the 198th and 250th tyrosine amino acid on HGF. So, using rat cell cultures, we developed and screened a series of antibodies that would specifically bind to these areas and block nitration," continues Tatsumi.

From Science Daily

In order to produce offspring from xenotransplanted ovaries, Japanese researchers at Niigata University and University of Toyama conducted a study to establish a system to produce offspring from eggs obtained by transplanting rat ovaries into mice.

From Science Daily

The researchers implanted rat ovaries under the renal capsules of immunodeficient mice and confirmed their viability.

From Science Daily

Then, they administered hormones related to oocyte development and succeeded in obtaining mature rat eggs.

From Science Daily

These eggs were found to develop normally when fertilized in vitro and to become embryos or offspring when transplanted into the rat uterus.

From Science Daily