a type of animal, such as a snake or lizard, whose body temperature changes according to the temperature around it, and that usually lays eggs to have babies.——朗文当代大辞典

Originally: a creeping or crawling animal. In later use: spec. an animal of the vertebrate class Reptilia, the members of which are characterized by having a dry impervious skin covered in horny scales.——牛津当代大辞典  @en