any of a class of usu cold-blooded air-breathing vertebrates, usu covered with scales or bony plates, that includes the alligators and crocodiles, lizards, snakes, turtles, and extinct related forms, e.g. the dinosaurs, and have a bony skeleton and a body usu covered with scales or bony plates: class Reptilia
informal a grovelling or despicable person
reptilian adj
[Middle English reptil via French or late Latin from Latin reptus, past part. of repere to creep]