What is the meaning of the word "positive"?

Definitions:

characterized by or displaying affirmation or acceptance or certainty etc. adjective
- a positive attitude
formally laid down or imposed adjective
- positive laws
greater than zero adjective
- positive numbers
having a positive charge adjective
- protons are positive
indicating existence or presence of a suspected condition or pathogen adjective
- a positive pregnancy test
involving advantage or good adjective
- a plus (or positive) factor
reckoned, situated or tending in the direction which naturally or arbitrarily is taken to indicate increase or progress or onward motion adjective
- positive increase in graduating students