촉매가 · 촉매를
catalyst
Example
그 사건은 사회 변화의 촉매 역할을 했습니다.
That incident served as a catalyst for social change.
Word parts
촉 touch+매 go-between
Literally 'touching go-between' — it triggers a reaction without being used up.
Good to know
Pronounced [총매]; used figuratively like English: 변화의 촉매가 되다.