opposition

1. (astronomy) The apparent relative position of two celestial bodies when one is at an angle of 180 degrees from the other as seen from the Earth.

2. (politics) A political party or movement opposed to the party or government in power.Examples: "leader of the opposition"

3. (law) In United States intellectual property law, a proceeding in which an interested party seeks to prevent the registration of a trademark or patent.

4. (chess) A position in which the player on the move must yield with his king allowing his opponent to advance with his own king.

5. (logic) The difference of quantity or quality between two propositions having the same subject and predicate.