also rat's-tail, used since 16c. of conditions or devices held to resemble a rat's long, hairless tail in some sense, including "lank lock of hair" (1810); "end of a rope" (1867); from rat (n.) + tail (n.1).
权威例句
1. If I don't send a picture, he will smell a rat.
如果我不寄出照片,他将有所察觉。
2. They were accused of encouraging children to rat on their parents.
他们被指控唆使儿童告发自己的父母。
3. Captain Hardnose certainly ran that rat over the hill.
哈得诺思上尉当然要求那个告密者离职了.
4. The lab assistant injected the rat with the new drug.