Positive

In common usage positive is sometimes used in affirmation, as a synonym for "yes" or to express "certainty".
In mathematics, a number is called positive if it is bigger than zero. See negative and non-negative numbers.
In functional analysis, a bounded linear operator is positive if its spectrum consists of positive real numbers.
In physics, one distinguishes positive and negative electric charges.
If a medical test for a certain disease is applied, the outcome is termed positive if the disease is detected.
In the humanities and social sciences, a theory is called positive if it aims to describe what is the case as opposed to what ought to be the case. See positive (social sciences).
In philosophy, positivism is the name for theories which aim to be based on facts alone, eschewing metaphysics and religion.