老鼠；耗子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
老鼠药
2.
(informal)
讨厌的人；卑鄙的小人；骗子an unpleasant person, especially one who is not loyal or who tricks sb