ETYM French, from Latin oppositio. Related to Opposite.
In astronomy, the moment at which a body in the Solar System lies opposite the Sun in the sky as seen from the Earth and crosses the meridian at about midnight.
Although the inferior planets cannot come to opposition, it is the best time for observation of the superior planets as they can then be seen all night.
1. The relation between opposed entities; SYN. oppositeness.
2. A direction opposite to another.
3. A contestant one is matched against; SYN. opponent, opposite.
4. A body of people united in opposing something.