catalyst

noun

1. A substance that increases the rate of a chemical reaction without being consumed in the process.

   “Enzymes, the catalysts of biological systems, are remarkable molecular devices that determine the pattern of chemical transformations.”

2. (figuratively)Something that encourages progress or change.

   “Economic development and integration are working as a catalyst for peace.”

   “It was a morning baptized by my first cup of coffee, freshly brewed over a gravel-bar fire, while they celebrated with the stronger catalyst of sour-mash whiskey in their fishing-vest cups.”

   “Israel's fear for the reactor—rather than Egypt's of it—was the greater catalyst for war.”

   “Rosa Parks was a true catalyst for change and she was only one person. Hearing about Rosa Parks and her protest showed me that there is hope for me and all the students in Ms. G's classes to truly be catalysts for change.”

   “He [countertenor Anthony Roth Constanzo] also enjoys being the catalyst whereby opera fertilises other art forms: recently, he's collaborated with Japanese kabuki actors, and a project with dancers from New York City Ballet is in the offing.”

3. An inciting incident that sets the successive conflict into motion.

   “The current view by both Labour and Conservative politicians is that the state of the UK railway is unsustainable, and the pandemic acted as a catalyst in exposing its weaknesses.”

4. A catalytic converter.
5. An object that facilitates the casting of a spell (such as a magic wand).