1
- a 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.鼠; 耗子。
1.1
- Family Muridae: many genera, including Rattus (the Old World rats), and several hundred species.鼠科：多属, 包括大鼠（东半球的家鼠属）和数百个种。
2
- informal a person regarded as despicable, especially a man who has been deceitful or disloyal〈非正式〉卑鄙小人（尤指欺诈或变节者）。
2.1
- an informer坐探, 告密者。
3
- with modifier N. Amer. a person who is associated with or frequents a specified place〈北美〉老是出没游逛于某处的人, 常客：
a wharf rat.
码头无业游民。
4
- US a pad used to give shape and fullness to a woman's hair〈美〉（为头发定型做出饱满效果的）女用发垫。
exclamation
rats
- informal used to express mild annoyance or irritation〈非正式〉胡说, 去你的（用以表示轻度烦恼, 恼怒）。
(ratted, ratting)no obj.
1
- usu. as noun ratting(of a person, dog, or cat) hunt or kill rats（人, 狗, 猫）捕（捉）老鼠; 灭鼠。
2
- informal desert one's party, side, or cause〈非正式〉变节, 背叛; 当工贼。
3
- with obj. US shape (hair) with a rat〈美〉用发垫给（头发）定型。
词源
Old English ræt, probably of Romance origin: reinforced in Middle English by Old French rat. The verb dates from the early 19th cent.
短语动词
rat on （〈美〉亦作rat someone out）
1
- informal inform on (someone) to a person in a position of authority告发：
men will literally choose death over ratting out another prisoner.
男人们确实宁肯死掉也不愿告发其他囚犯。
1.1
- break (an agreement or promise)撕毁（协议）; 违背（诺言）：
he accused the government of ratting on an earlier pledge.
他指控政府不兑现早先的承诺。