Before revision: A sign is an object, quality, event, or entity whose presence or occurrence indicates the probable presence or occurrence of something else.New Oxford American Dictionary A natural sign bears a causal relation to its object—for instance, thunder is a sign of storm, or medical symptoms a sign of disease.
After revision: A SIGN is an object, quality, event, or entity whose presence or occurrence indicates the probable presence or occurrence of something else.New Oxford American Dictionary A natural sign bears a causal relation to its object—for instance, thunder is a sign of storm, or medical symptoms a sign of disease.