行動

1. Origins, structure, and basic meaning

• Structure: 行動 is read as こうどう and is a noun and する verb for action or conduct carried out with purpose or judgment.
• Basic usage: Acting calmly appears in 落ち着いて行動する, while quick action preventing loss appears in 素早い行動が損失を防ぐ.

2. Common pitfalls and similar expressions

• Manner and result of action
  • Express the manner adverbially and the result caused by action with が.
• Difference from 動作
  • 行動 covers purposeful conduct rather than an individual bodily movement.