rat

 
Pronunciation: /rat/

noun

  • 1a rodent that resembles a large mouse, typically having a pointed snout and a long 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
  • 2 informal a despicable person, especially a man who has been deceitful or disloyal: her rat of a husband cheated on her
  • an informer: he became the most famous rat in mob history
  • 3 [with modifier] North American informal a person who is associated with or frequents a specified place: LA mall rats
  • 4US a pad used to give shape and fullness to a woman’s hair.

exclamation

(rats) informal
  • used to express mild annoyance or irritation.

verb (rats, ratting, ratted)

[no object]
  • 1 (usually as noun ratting) hunt or kill rats: ratting is second nature to a Jack Russell
  • 2 informal desert one’s party, side, or cause: many of the clans rallied to his support, others ratted and joined the King’s forces
  • 3 [with object] US shape (hair) with a rat.

Phrasal Verbs

rat on

(also North American rat someone out) informal inform on (someone): he refused to rat on his buddies
break (an agreement or promise): he accused the government of ratting on an earlier pledge

Origin:

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