反対

1. Origins, structure, and basic meaning

• Structure: 反対 (はんたい) can denote opposition or the opposite side. 反対する is an action verb, whereas 反対側 is a compound location noun.
• Basic usage: 計画に反対する expresses disagreement with a plan; 駅の反対側 identifies a place across from the station.

2. Common pitfalls and similar expressions

• Opposing an idea versus the opposite side
  • The target of 反対する is marked by に, while the reference point for 反対側 precedes it with の. Abstract opposition and spatial location require separate readings.