decide · fixed

1. Origins, structure, and basic meaning

• Structure: 定 conveys setting something or its being fixed.
• Basic usage: 定める（さだめる） is a verb meaning to set rules, deadlines, or similar terms, while 予定（よてい） means a future plan or schedule.

2. Common pitfalls and similar expressions

• Setting rules and making future plans
  • 規則を定めた means that rules were set. 定める is also used when a deadline is explicitly stipulated.
  • 予定 can refer to a plan to see a film or a departure schedule. As in the example of a departure delayed by rain, a 予定 can still change.