rat¹/ræt; ræt/ n [C] 1 an animal like a large mouse with a long tail 大老鼠: There was a dead rat on the cellar steps. 地下室的台阶上有一只死老鼠。 2informal spoken someone you trusted who deceives you 【非正式，口】 卑鄙小人，骗子，叛徒: But you promised to help us — you rat! 可是你答应过要帮我们忙的，你这言而无信的小人！