opposite (adjective): position

We put the adjective opposite before a noun when we are talking about one of a pair of things that naturally face or contrast with each other.

• I think the picture would look better on the opposite wall.
• She went off in the opposite direction.
• I’ve got exactly the opposite opinion to yours.
• His brother was fighting on the opposite side.

We put opposite after the noun when it means ‘facing the speaker or listener’ or ‘facing a person or place that has already been mentioned’.

• I noticed that the man opposite was staring at me. (not … the opposite man was staring at me.)
• The woman she was looking for was in the house directly opposite.

note

For opposite and contrary, (see here).