an animal with a long thin body and no legs, that often has a poisonous bite.——朗文当代大辞典

One or other of the limbless vertebrates constituting the reptilian order Ophidia (characterized by a greatly elongated body, tapering tail, and smooth scaly integument), some species of which are noted for their venomous properties; an ophidian, a serpent. Also, in popular use, applied to some species of Lacerta, and to certain snake-like amphibians.——牛津当代大辞典  @en