the note on big cats is quite correct: tigers, lions, cougars (!), leopards, jaguars are all considered "big cats". all have kind-of-round pupils. i'm not sure whether cheetahs are considered big or small. one distinctive characteristic: big cats can roar. that would make cheetahs "small". but there are more small cats than just the domestic ones. and i am not sure about whether the round pupil is a characteristic on small cats.