契機

1. Origins, structure, and basic meaning

• Structure: 契機 (けいき) means an occasion or turning point that initiates change. 契機になる presents the resulting role; 契機に sets the starting point.
• Basic usage: A travel encounter prompts the study of painting, while an accident triggers a full review of procedures.

2. Common pitfalls and similar expressions

• Encounter opening new study and accident prompting reform
  • 契機になった predicates the role an event acquired; を契機に makes it the reference point for later change. The word implies more than mere chronological sequence.