/ ræt; NAmE / noun , verb
■ noun
1.
a small animal with a long tail, that looks like a large mouse, usually considered a pest (= an animal which is disliked because it destroys food or spreads disease) :
rat poison
—compare rug rat
2.
( informal , disapproving ) an unpleasant person, especially one who is not loyal or who tricks sb
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IDIOMS
see sink verb , smell verb
■ verb
( -tt- )
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PHRASAL VERBS
- rat on sb
- rat on sth
••
WORD ORIGIN
Old English ræt , probably of Romance origin; reinforced in Middle English by Old French rat . The verb dates from the early 19th cent.