A trigger, opportunity, or motive that causes something to start or happen; an occasion or cue that prompts an action.
留学が英語を好きになったきっかけだ。
Studying abroad was the reason I came to like English.
その小さな出会いが歌手をめざすきっかけになった。
That small encounter was the trigger for aiming to become a singer.
健康診断での指摘が禁煙のきっかけになった。
A note on my health checkup became the impetus to quit smoking.
テレビで見たドキュメンタリーがボランティアを始めるきっかけだった。
A documentary I saw on TV was the reason I started volunteering.