Opposite

1. An antonym. High and low, fat and thin are antonyms because they have opposite meanings.
2. Located directly across from something else, or from each other. She saw him walking on the opposite side of the road.
3. Of either of two complementary or mutually exclusive things. He has had a lot of success with the opposite sex.
4. Facing in the other direction. They were moving in opposite directions.
5. Facing, or across from. He parked the car opposite the store.
6. In a complementary role to. He played opposite Marilyn Monroe.
7. (botany) Growing in pairs on either side of a stem. This plant has opposite leaves.
8. Altogether different, as in nature, quality, or significance. The effect of the medicine was opposite to that intended.