互い

1. Origins, structure, and basic meaning

• Structure: 互い (たがい) is a noun-like expression meaning each other or a mutual relationship between two or more parties.
• Basic usage: It appears when people listen to each other's ideas or compensate for one another's weaknesses.
  • 二人は互いの考えを最後まで聞いた。 — The two listened to each other's thoughts to the end.
  • 互いに不足を補えば作業は早く終わる。 — Work finishes faster when we make up for each other's weaknesses.

2. Common pitfalls and similar expressions

• Possession and reciprocal action
  • 互いの modifies a noun, as in 互いの考え, while 互いに marks an action directed reciprocally, as in 互いに補う.