I mean circular, in that the definition's reference each other. E.g. if the definition for "happy" was "not sad" and the definition for "sad" was "not happy. If

I mean circular, in that the definition's reference each other. E.g. if the definition for "happy" was "not sad" and the definition for "sad" was "not happy. If you didn't know one of those words already, the dictionary would be useless.